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

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Dolly Varden
Salvelinus malma

What do they look like?

The Dolly Varden is a trout-like char with pale pink, lilac, or red spots along the flanks. It has an olive-green to brown body, a round shaped head with an upper jaw that curves slightly upwards. Fins are generally transparent and without black spots on the dorsal fin; pelvic and anal fins are often white or creamy on the leading edge with a single thin black and thin red line behind; the caudal fin is slightly forked. Relative to bull trout, the spots on the back are small and crowded and bull trout have a broader flattened head shape.

Dolly Varden and bull trout are difficult to distinguish in the field. Where they coexist, the life history of adults is usually strikingly different. Typically, adult Dolly Varden are small (10-20 cm), stream-resident, and feed on drift; whereas adult bull trout are large (55-95 cm), migratory, and piscivorous. As far as is known, Dolly Varden and bull trout hybridize (interbreeding of two different species) wherever they coexist. Despite this persistent hybridization, the two species maintain themselves as separate entities with life histories adapted to two alternative ecologies. In the Williston area, Dolly Varden coexist with bull trout for part of their life cycle in the upper Finlay drainages (tributaries to Thutade Lake).

Where do they live?

Dolly Varden are a northern species and usually are associated with cool waters (i.e., waters where summer temperatures rarely exceed 20 °C and normally are <15 °C). In the Williston/Dinosaur drainage basin Dolly Varden are confined to the upper Finlay system (Thutade Lake tributaries, upper Finlay River below Cascadero Falls, some upper Ingenika tributaries, and some Fredrickson Creek tributaries).

Habitat use by adult Dolly Varden is influenced by both life-history type and the presence of other fish species. Since the upper Finlay populations are all stream-residents, life-history type is not a problem; however, in this system the presence of bull trout probably affects habitat use by adult Dolly Varden. In areas of contact, Dolly Varden are typically stream residents and bull trout are riverine or adfluvial. Habitat use by adult Dolly Varden and juvenile bull trout has been examined in Thutade Lake tributaries. There was considerable overlap between the species - they used the same hydraulic habitat types (main channel pools, main channel riffles, side channel pools, side channel riffles) in similar proportions during both day and night. At night, however, adult Dolly Varden were found in deeper and, perhaps, faster water than juvenile bull trout.

Juvenile Dolly Varden shift habitats as they grow and move to deeper, faster water as they increase in size. They are associated with riffles and pools but also use deep side-channels. During the day they remain close to cover, such as large rocks, woody debris, root wads, and undercut banks, but at night they disperse and are less strongly associated with cover.

Newly emerged Dolly Varden fry are denser than water and associated with shallow (<5 cm deep) stream edges. Here, they are found in, and around, coarse gravel and cobbles interspersed with boulders and especially in areas of low water velocities (<20 cm/s) such as side-channels and shallow bays. In most populations the fry remain in this habitat during their first summer but shift to deeper, faster water as they grow.

What is their life like?

In British Columbia, Dolly Varden display three life-history patterns: an anadromous form that migrates between fresh water and the sea, a stream-resident form that spends its entire life in rivers and streams, and an adfluvial form that lives most of its adult life in lakes but spawns in streams. Most populations of Dolly Varden in the Williston/Dinosaur system are stream residents; however, there is an adfluvial population associated with Duncan Lake in the Firesteel watershed and possibly another in the upper Ingenika watershed.

Like all char, Dolly Varden spawn in the fall, although the exact time and place of spawning varies with temperature and life history type. With the exception of stream-resident populations that usually spawn locally, a migration often precedes spawning. As far as is known, all Dolly Varden spawn in running water during the day. Spawning females are usually accompanied by a dominant male.

Females select the spawning site and dig a nest (redd). The size and depth of the redd, and the size of spawning gravel, varies with female size. In the upper Peace system, the only observations on Dolly Varden spawning are for stream-resident populations associated with Thutade Lake. Here, spawning peaks in late September at water temperatures of about 6 °C. Females in this population usually excavate redds in shallow (<15 cm), low velocity (<40 cm/s) headwaters. Typically, the redds are small (<0.5 m 2).

Like most fish, egg number in Dolly Varden is a function of female body size and varies within and among populations. Females in headwater populations, such as those in the upper Finlay drainage, typically breed at a small size (<200 mm) and produce 200-500 eggs. The eggs incubate in the gravel over winter and the fry emerge near the beginning of June. Dolly Varden fry are smaller than sympatric bull trout fry and typically emerge at less than 20 mm. In the upper Finlay, depending on stream temperature, young Dolly Varden reach 25-40 mm by the end of their first summer, about 60 mm in their second summer, and about 80 mm by the end of their third summer. Some males mature at the end of their fourth summer (>115 mm) and most fish of both sexes mature in their fifth growing season (4+). Maximum age in these populations is about nine years (8+).

What do they eat?

Stream-resident adults feed primarily on the nymphs and larvae of aquatic insects (e.g., mayflies, caddisflies, stoneflies, and chironomids). When feeding during the day, these fish remain close to the bottom and most feeding movements are directed towards insects drifting near the bottom. Occasionally, however, they rise to the surface and take capsized terrestrial insects. The fry feed primarily on chironomid larvae but gradually shift to larger prey (predominately insect nymphs) as they grow.

What is their distribution? Dolly Varden are continuously distributed in coastal areas around the North Pacific Ocean. In Asia, they extend south to Korea and northern Japan, and in North America from the Arctic Slope of Alaska south to the Olympic Peninsula in Washington. In British Columbia, Dolly Varden are primarily a coastal species and regularly enter the sea. In the Skeena system, and perhaps in other north coast drainages, they penetrate farther inland. Apparently, there have been headwater transfers of Dolly Varden from the Skeena into the upper Fraser (Stuart system) and upper Peace (Finlay system). There are also Dolly Varden in the B.C. headwaters of the Liard River (Mackenzie system) that presumably crossed into the Liard from either the Stikine or Taku river systems.

View Peace Williston distribution map.