Lake trout illustration credit: U.S. Fish and Wildlife Service.
Lake Trout
Scientific Name: Salvelinus namaycush
"Salvelinus" is an old name for char, the salmonid group that lake trout belongs to.
"namaycush" is a First Nations' name meaning 'dweller of the deep'.
Lake Trout were once a dominant trout across much of Ontario, including in particular the Great Lakes, where they supported a large commercial fishery. Fishing pressure, habitat loss and the accidental introduction of the invasive sea lamprey combined to significantly reduce lake trout populations in many areas. Lamprey control, a reduction in fishing pressure and stocking programs have resulted in a population rebound in some, but not all locations. The history of lake trout in Ontario is a cautionary tale. Find out more in Activity 1.
Description
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Credit: Greater Yellowstone Science Learning Center |
- an elongate, trout-like body with a stout head
- a large mouth; snout usually overhangs the lower jaw when the mouth is closed
- white or yellowish spots on a dark green to grayish background
- the underside is white
- sometimes the paired fins are an orange-red colour, especially in northern populations; white leading edge on lower fins, and,
- tail is deeply forked.
Similar To
- Brook trout (especially lake-resident)
- Brown trout
Key Identifying Features
- Deeply forked tail
- Light spots on dark body. No red spots
Size
- Average length in Ontario: 30 - 80 cm (12 - 31 in.)
- Ontario record: weight – 28.63 kg (63.12 lbs.), length – 130.81 cm (51.50”), Lake Superior 1952. (A 102 pound lake trout was taken in a gillnet in Lake Athabasca, Saskatchewan, in 1961).
Distribution and Habitat
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| North American distribution of lake trout is shown in pink. |
- In North America, broadly distributed in northern and some mountain areas. Found almost exclusively in deep, cold, oligotrophic (low nutrient) lakes. Widely introduced outside its native range.
- In Ontario found in less than 1% of Ontario’s lakes – the lakes deep enough to hold cold water throughout the year. Includes the Great Lakes and some large river systems.
- In Ontario, found in suitable streams and lakes south of a line from Kenora to Kesagami Lake.
- It is believed that approximately 20% of the lake trout lakes in the world are found in Ontario.
- Require well-oxygenated (> 7 mg/l) water.
- Prefer open water that is 48-52 degrees Fahrenheit or 9-11 degrees Celsius.
Food
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- Juveniles: plankton, insect larvae, insects, and other invertebrates.
- Adults: smaller fish.
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Predators
- Larger fish, including lake trout. Fish are too deep for diving predators.
- Numerous parasites, including sea lamprey
- Humans.
Reproduction
- Inland rainbow trout spawn in streams from March to May.
- Spawn over reefs of cobble, rubble or gravel, 2-3 m (6.6-9.8 ft.) deep, often near shore.
- Do not create nests, but males will fan the bottom clean of silt.
- Spawning temperature is usually between 10.0-12.0ºC (50-53.6ºF).
- Fall or early winter spawning, mostly at night.
- Several males will mate with a singe female.
- Eggs overwinter four to six months before hatching.
- No parental care is given.
- If conditions are favourable, mature fish will spawn every year or every other year
Management Tips
- Continue to control sea lamprey in the Great Lakes.
- Ensure that fishing limits and opportunities are in line with populations; respect fishing regulations.
- Where possible, emphasize growth of natural populations rather than stocking.
- Protect habitat and habitat quality, particularly in the hypolimnion (deeper waters).
- Protect and rehabilitate riparian zones to prevent erosion, pollutant run-off and increased water temperatures.
- Use "best management practices" with respect to urban and rural development, agriculture, forestry, and other industry.
- Ensure that septic tanks are not faulty.
- Reduce hard surfaces such as concrete near water bodies that results in higher water run-off temperatures.
- Reduce greenhouse gas emissions driving climate change that contributes to increased water temperatures.
- Collect long-term data to help monitor the health of aquatic communities, and identify and address problems.
