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Montana Animal Field Guide

Montana Field Guides

Lake Trout - Salvelinus namaycush

Species of Concern

Global Rank: G5
State Rank: S2
* (see State Rank Reason below)

Agency Status


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State Rank Reason (see State Rank above)
This species is a glacial relic in Montana known from native (never-stocked) populations occurring in Waterton Lake, Glenns Lake, Cosley Lake, and St. Mary Lake in Glacier National Park and Lower St. Mary Lake on the Blackfeet Indian Reservation, as well as a couple of small populations in the upper Missouri River basin. Otherwise, all other populations in the state are introduced.
General Description
The Lake Trout is a char of the same genus as Bull Trout and Brook Trout. Lake Trout are native in the St. Mary and Missouri River drainages and have been introduced to a few other scattered mountain lakes, Flathead Lake, and Fort Peck Reservoir. Lake Trout are a major game fish in much of Canada and were at one time a staple of the Great Lakes fishery. In Montana, the Lake Trout of Flathead Lake have achieved trophy status, growing to 42 pounds. Lake Trout inhabit very deep, cold lakes, living in water up to 200 feet deep. They spawn in the fall on the rocky substrate of the shoreline. They scatter or broadcast their spawn, a rarity in the trout group. Small Lake Trout feed on plankton and aquatic invertebrates but fish over 2 to 3 pounds eat a fish diet. Lake Trout are a highly-prized food fish in Canada and are catching on as a game fish in Montana with the advent of downriggers, electronic fish finders, and other specialized techniques.

Diagnostic Characteristics
May have pale wavy lines on back. Fins may have traces of orange.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.

Summary of Observations Submitted for Montana
Number of Observations: 1546

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Deep, cold lakes and reservoirs (Montana Department of Fish, Wildlife, and Parks 2003). Deep cold water lakes and reservoir with some rocky bottom and on abundance of forage fish. Spawns over rocky shoal areas in lakes in depths from 10 to 120 feet.

Food Habits
Young feed on plankton and aquatic invertebrates. Diet is largely fish after reaching 2-3 lbs. in weight.

Reproductive Characteristics
Broadcasts spawn Oct-Nov. Eggs hatch in following March or April when water temps. Reach 34-38 degrees F. Fry soon move into deep water. No parental care.

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Citation for data on this website:
Lake Trout — Salvelinus namaycush.  Montana Field Guide.  .  Retrieved on , from