The Peace/Williston Fish and Wildlife Compensation Program (PWFWCP)

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Lake Trout
Salvelinus namaycush

What do they look like?

A trout-like char, heavily spotted with irregularly shaped light spots on the back, sides, and on the dorsal and caudal fins. Unlike other char in our area, the spots on lake trout are grey or whitish but never coloured and the tail is deeply forked (in lake trout the centre rays on the tail are about half the length of the longest outer rays while in other char the centre rays are almost as long as the longest outer rays). The lower fins are slightly orangish with white leading edges.

Where do they live?

Like most char, lake trout prefer cool water. Adults can tolerate temperatures ranging from near 0 °C to about 18 °C but they prefer temperatures around 10 °C. Seasonally, adult lake trout shift their vertical distribution in response to temperature changes. In the spring, when lakes are essentially homothermous, adult lake trout are found at all depths. As lakes stratify, however, they move to deeper, cooler water. If bottom waters become oxygen depleted (<4 mg/l), they move up in the water column. Thus, in small lakes they can be trapped between the thermocline and an oxygen depleted bottom layer.

Juvenile lake trout occupy similar habitats to those used by adults; however, they tend to occur in deeper water than adults. The temperature range occupied by juveniles is about 6-13 °C. After filling their swimbladders, lake trout alevins become neutrally buoyant and highly mobile. In some populations they remain in shallow water in the vicinity of the spawning site for several weeks, while in other populations fry are thought to move directly to deep water. One study suggests that a period of residence near the spawning site is necessary for imprinting (there is evidence that adults in some population's return to their natal spawning site).

What is their life like?

Little is known about the life history of lake trout in B.C. Like other char, lake trout spawn in the fall, usually when water temperatures drop below about 10 °C. In B.C., spawning dates vary with latitude and lake size (late September to November). So far, in B.C., spawning has only been recorded in lakes; however, elsewhere some populations spawn in rivers. Lake trout will spawn on a variety of substrates including broken rubble or angular rock interspersed with large boulders. Spawning depth is variable but usually ranges from about 5-50 m.

Since lake trout spawn at night, their spawning behaviour is not as well documented. They do not construct redds but some prespawning activities help to clean the substrate. As the eggs are released they are fertilized and fall into cracks and crannies between the rocks. No attempt is made to cover the eggs. Depending on female body size, fecundity varies from 500-20,000 eggs, and in many populations females do not spawn every year. As in most fish, development rate is a function of incubation temperature, and hatching times range from about 50 days at 10 °C to about 156 days at 2 °C. Fry (newly hatched larvae) are about 21 mm long and emerge from the substrate at night once the yolk sac is absorbed.

Generally, northern populations grow more slowly but live longer and reach a larger size than southern populations. Maturity in lake trout varies among populations but usually is reached at between 5 and 13 years. Lake trout in northern lakes are especially long-lived and fish 20 years and older are not uncommon. So far, the oldest lake trout aged by otoliths was 62 years old.

What do they eat?

Young-of-the-year lake trout forage primarily on plankton and the larvae of aquatic insects. As they grow, they add larger benthic organisms (e.g., amphipods and mollusks) to their diet and, if appropriate prey is available, they often switch to fish when they reach a length of about 35-40 cm. If fish are unavailable, lake trout remain planktivorous. Seasonal changes in diet are common and are associated with temperature. For example, in the spring adults and sub adults may forage in shallow water and near the surface. At this time minnows and terrestrial insects may be important in the diet. As the lake warms and stratifies, lake trout are separated from these food sources by a thermal barrier. Under such conditions they may switch to plankton and in the fall, as the lake cools, switch back to their spring diet.

What is their distribution? Originally, lake trout were restricted to northern North America but they have been widely introduced outside their native range in the United States and Canada. Their natural distribution lies almost entirely within glaciated areas and includes the southern islands in the Arctic Archipelago (Baffin, Southampton, King William, Victoria, and Banks islands). In B.C., the lake trout's natural range covers the upper and middle Fraser system (including the Thompson drainage) from the Kamloops-Shuswap region north, the upper Skeena, Nass, Stikine, Taku, and Yukon systems, as well as the Peace and Liard river systems.

View Peace Williston distribution map.