Lake Trout

On this page

• Species overview
• Fishery history
• Ecosystem context
• Science advice and research
• Sources

Species overview

Physical description

Lake Trout is a long fish with many light-coloured spots on its darker body. Some fish are silver, making the spots harder to see. In northern Canada, Lake Trout has orange or orange-red fins. Young Lake Trout often have 5 to 12 dark oval bands on their sides known as parr marks.

Lake Trout can grow up to 106 centimetres (cm) in length. During spawning, both male and female Lake Trout develop small breeding tubercles around the anal fin.

Lake Trout can successfully breed with Brook Trout to create a fertile hybrid called Splake or Wendigo.

Distribution

Lake Trout is native to northern North America but has been introduced to other areas such as:

• New Zealand
• South America
• Sweden
• the United States

Lake Trout occupies nearly all provinces and territories in Canada. In the spring, it is often found in surface waters after ice melts. As waters warm, Lake Trout moves into deeper, cooler waters (~10°C). It is often found at depths from 18 to 53 metres (m), but has been found as deep as 467 m. In the north, Lake Trout is found in shallower areas of lakes and in rivers.

Life cycle

Lake Trout spawns in the fall from August to November. Spawning occurs in lakes over large boulder or rubble bottoms at depths from 1 to 12 m. Water temperature for breeding is usually 8.9 to 13.9°C. Lake Trout returns to the same spawning grounds every year, a behaviour known as homing or philopatry.

Fertilized eggs drop between crevices in the rocky bottom and incubate for 4 to 5 months. Eggs hatch between March and June. In some areas, newly hatched young move into deeper waters to find food. In northern lakes, they may stay inshore for months or years before moving into deeper water.

Young Lake Trout eat mainly invertebrates, while adults are opportunistic and have a varied diet including:

• Cisco
• Alewife
• Sculpins
• Smelt

Lake Trout reaches maturity at age 6 to 7 years. In northern areas, it matures as late as 13 years old. Females can spawn every 2 to 3 years. Lake Trout can live for an average of 21 years and as long as 51 years.

Fishery history

Lake Trout is very important to commercial, recreational, and subsistence fisheries year-round. In many lakes, they are fished recreationally by fly or spin fishing in the spring or deep-set lines in the summer. In northern areas, deep trolling is not necessary as Lake Trout often occupies shallower waters.

Due to the popularity of angling for Lake Trout, population declines are being seen across much of its range. Lake Trout is particularly vulnerable to overfishing because it:

• has excellent flesh for consumption
• forms large aggregations for spawning
• has predictable migration and spawning times

Commercial fisheries use gillnets to catch Lake Trout. Northern populations were over-harvested for many years, leading to declines, particularly in Great Slave Lake. The total Canadian harvest declined dramatically in the 1960s.

Lake Trout is a valuable fish in the subsistence fisheries in the Inuvialuit Settlement Region of Northwest Territories. Lake Trout from the Husky Lakes has been used for generations for food. It used to be only accessible by snowmobile when conditions allowed; however, a highway was built which now allows year-round access.

A common Lake Trout management measure is hatchery rearing of young for release. For example, since 1892, hatchery fish were released in Nova Scotia to stock water bodies with Lake Trout. This was also successful in the Great Lakes and Cayuga Lake.

Ecosystem context

Lake Trout eggs are susceptible to predation by:

• Lake Whitefish
• Brown Bullhead
• Burbot

Lake Trout was heavily depleted in Lake Superior and nearly went extinct in Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario in the 1940s and 1950s. This was due to over-harvesting and the invasion of Sea Lamprey, which parasitizes Lake Trout. Other threats included:

• pollution (e.g., DDT)
• changes to prey availability and forage fish population
• habitat degradation
• increased habitat access

Lake Trout is susceptible to population decline because it:

• is long-lived, late-maturing, and slow-growing
• has a slow replacement rate
• lives in habitats with low-productivity

Science advice and research

Science advice and research for Lake Trout

Sources

• Great Lakes Fishery Commission 1984. Strategies for rehabilitation of Lake Trout in the Great Lakes: Proceedings of a conference on Lake Trout research, August 1983. Tech. Rep. No. 40.
• Kissinger et al. 2019. Assessment of Lake Trout populations within the Inuvialuit Settlement Region of Northwest Territories and Yukon, 2014-2015. Can. Manuscr. Rep. Fish. Aquat. Sci. 3181: vi + 34 p.
• Kissinger et al. 2020. Community-based Lake Trout (Salvelinus namaycush) monitoring program in Husky Lakes NT, 2014-2015. Can. Data Rep. Fish. Aquat. Sci. 1302: v + 16 p.
• McPhail and Lindsey 1970. Freshwater fishes of northwestern Canada and Alaska. Fish. Res. Board Can. Bulletin 173.
• Scott and Crossman 1973. Freshwater fishes of Canada. Department of Fisheries and Oceans. Fish. Res. Board of Can. Bulletin 184.
• Semple 1969. Hatchery plantings of Brown Trout, Lake Trout, Rainbow Trout and Lake Whitefish in Noa Scotia, and subsequent angling success. Resource Development Branch. Manuscr. Rep. 69-1.
• Siesennop 2000. Estimating potential yield and harvest of Lake Trout Salvelinus namaycush in Minnesota’s Lake Trout lakes, exclusive of Lake Superior. Minn. Dep. Nat. Res. Invest. Rep. 487.
• Yaremchuk 1986. Results of a nine year study (1972-80) of the sport fishing exploitation of Lake Trout (Salvelinus namaycush) on Great Slave and Great Bear Lakes, NWT: the nature of the resource and management options. Can. Tech. Rep. Fish. Aquat. Sci. 1436: vi + 80 p.