Freshwater Fishes of the Columbia Basin Return to Table of Contents Return to Species List

Native Fishes: Family Salmonidae
(Trout, Salmon, Char, Whitefish)

Distribution of native trout and salmon species
of the Columbia Basin (RBCM Collections)

Distribution of native whitefish and char in
the Columbia Basin (RBCM Collections)

Oncorhynchus clarki lewisi (Girard)	Westslope Cutthroat Trout
Oncorhynchus=hooked snout clarki lewisi=after Cpt. William Clark and Cpt. Meriwether Lewis of the Lewis and Clark expeditions

The common name 'Cutthroat' comes from the distinct red or orange slash mark under the lower jaw of this species, which makes it appear as though it has a sliced throat. The presence of slashmarks under the chin and the extension of the upper jaw beyond the margin of the eye separate Westslope Cutthroat Trout from the closely related Rainbow Trout.

Two forms of Cutthroat Trout are recognized in Canada. The Pacific variety, Coastal Cutthroat Trout (Oncorhynchus clarki clarki) ranges from Alaska to northern California in fresh, brackish and salt water with many populations having anadromous reproductive migrations. The Westslope Cutthroat Trout (Oncorhynchus clarki lewisi) occurs in southeastern British Columbia, southwestern Alberta and Montana (Scott and Crossman 1973). The Westslope Cutthroat Trout differs from its coastal relatives by having spots restricted to the posterior portion of its body and lacks the distinct red lateral band typical of many Coastal Cutthroat Trout populations. The Westslope Cutthroat subspecies designation refers to the western slopes of the Rocky Mountain Divide although this variety occurs east of the Rocky Mountains. In British Columbia Coastal Cutthroat Trout and Westslope Cutthroat Trout are separated by a narrow band through the Interior Plateau where the closely related Rainbow Trout (Oncorhynchus mykiss) outcompete Cutthroat Trout for foraging and spawning habitat (McPhail 1998). Occasionally in overlapping ranges, Cutthroat Trout and Rainbow Trout hybridize. There has been some concern that translocated (purposefully transplanted) Rainbow Trout populations have had a deleterious effect on native Westslope Cutthroat Trout populations (Nelson 1965).

Cutthroat Trout frequent lakes and streams with stepping pools and back-eddies. Spawning occurs in small gravel-laden streams during the late spring and early summer, once water temperatures reach about 10° C (Scott and Crossman 1973). Females prepare a redd (salmonid nest) by thrashing their tails while laying on their side to displace gravel until the pocket is about 15 cm deep. Males are aggressive towards other males that appear too close to courted females or her redd. After the spawning ritual is performed, females bury the fertilized eggs in the nest by dislodging gravel on the upstream edge of the redd.

Cutthroat are native and thrive in all cool water drainages of the upper Columbia, upper Kootenay and Flathead systems. The species is less abundant in the lower Columbia and lower Kootenay, and native populations are absent from the Kettle, Okanagan and Similkameen rivers.

Oncorhynchus mykiss (Walbaum)	Rainbow Trout
Oncorhynchus=hooked snout mykiss=vernacular name in Kamchatka

The native distribution of Rainbow Trout in North America includes coastal and interior areas west of the Continental Divide, extending south from Alaska to northern Mexico. The popularity of Rainbow Trout as a sport fish has made it a globally translocated species, with successful introductions in New Zealand, Australia, Japan, Europe, Africa and South America (McCrimmon 1971).

Many Rainbow Trout populations have been translocated (the introduction of native species into waters they did not originally inhabit) through efforts aimed at improving angling opportunities, and it is presently difficult to differentiate the native, wild varieties from domesticated strains.

Rainbow Trout are highly variable in life history characteristics and appearance, with up to 16 different historic subspecies being designated throughout the species range. Modern taxonomists loosely agree that there are three potential subspecies of Rainbow Trout in British Columbia. These are: Columbia River Redband Trout (Oncorhyncus mykiss gairdneri), coastal resident Rainbow Trout, including the anadromous Steelhead Trout (Oncorhyncus mykiss irideus), and the Athabascan Rainbow Trout (Oncorhyncus mykiss subsp.) of the Mackenzie drainage (Taylor and Haas 1996).

Rainbow Trout are a common species throughout the Columbia Basin, and this species displays a bewildering array of life history and phenotypic variability within the region. The large Gerrard Rainbow Trout (up to 15 kg) from Kootenay Lake and the "yellow fin" Rainbow Trout of the Arrow lakes are unique in terms of their large trophy size and distinct colouration. The steep headwater drainages of the Selkirk Mountains contain mature, dwarf varieties of Rainbow Trout that maintain juvenile characteristics throughout life.

Inland representatives of Rainbow Trout are characteristically a stream and lake fish. Spawning occurs in both inlets and outlets of lakes and small streams with fine, clean gravel during early spring when the water reaches 10-15.5° C (Scott and Crossman 1973). Females dig a redd in riffles above a pool by turning on their sides and thrashing their tails to create a depression of about body length. During the construction of the redd the female may be accompanied by many aggressive males -- usually the largest of the males is dominant and most active in courtship. After the eggs are fertilized, the female covers the nest with gravel and the eggs hatch four to seven weeks later.

Rainbow Trout are often difficult to differentiate from the closely related Cutthroat Trout, and the species often hybridize in areas where their distributions overlap. The upper jaw length of Rainbow Trout never extends past the hind margin of the eye, nor do they exhibit the diagnostic red or orange slash under the chin that is typical of Cutthroat Trout.

Oncorhynchus nerka (Walbaum)	Sockeye Salmon (Kokanee)
Oncorhynchus=hooked snout nerka=Russian name for anadromous form

The deep-red oily flesh of Sockeye Salmon makes it one of the most prized and valuable of the Pacific Salmon. Sockeye are distributed along the Pacific Rim from the Klamath River in California, north along the coast of British Columbia to Alaska, and westward to the Kamchatka Peninsula through to Japan. Sockeye exhibit a variety of life history patterns, with mature fish characteristically making long seasonal, homing migrations of hundreds of kilometres from the ocean to their natal waters, which are usually associated with large lake systems. One of the most striking features of migrating Sockeye is their "toothy" hooked kype and spawning dress. Both sexes develop brilliant crimson dorsal surfaces and green heads, although females are usually less colourful than males.

Juveniles rear in lakes, feeding on zooplankton for two to three years before emigrating to the ocean. Return migrations are made after three to four summers at sea, although some precocious males (jacks) return after a single summer of ocean growth. Most Sockeye populations are anadromous, there are, however, distinct non-migratory populations known as Kokanee.

Kokanee reside permanently in freshwater, and evidence suggests that they have diverged repeatedly from Sockeye populations since the retreat of the last glacial period. Because Kokanee are derived from migratory stocks of Sockeye Salmon, many populations differ in life history, behaviour and phenotype between and within some lakes. In Okanagan Lake there are at least two unique forms of Kokanee: one is a beach shore spawner and the other -- larger crimson variety -- is a stream spawner (Taylor et al. 1997). The Kokanee of Kootenay Lake can be divided into at least three homing races, each returning to their parent streams to spawn (Vernon 1957). Although there have been no known Kokanee extinctions, decreasing lake productivity (nutrient flow) and the introduction of exotic invertebrate shrimp (mysids) have been factors contributing to declining Kokanee numbers in Kootenay, Okanagan and Arrow lakes. Most of the larger lakes in the Columbia Basin have rehabilitation programs in place to help boost Kokanee numbers.

In the Canadian portion of the Columbia Basin, the only remaining anadromous Sockeye Salmon runs return to spawn in the Okanagan River between Osoyoos and Vaseau lakes. Kokanee are widely distributed in large lakes and associated tributaries, except for isolated regions not historically visited by Sockeye runs in the upper Columbia, upper Kootenay and Flathead drainages.

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Salvelinus confluentus (Suckly)	Bull Trout
Salvelinus=an old name for char confluentus=flowing together

Bull Trout are endemic to both sides of the Continental Divide in northwestern North America from southern Alaska to California. This variable cold-water species is not a true trout as its common name implies, but rather a char of the genus Salvelinus. Bull Trout are a robust species well suited to the mountainous terrain typical of British Columbia and the remainder of the North American Cordilleran.

The nomenclature and distribution of the Bull Trout has been a recent point of debate for salmonid taxonomists (Haas and McPhail 1991). Bull Trout are often difficult to distinguish from Dolly Varden Char (Salvelinus malma), and, until recently, they were considered the same species, the difference being distribution -- Dolly Varden is a coastal species and Bull Trout is an interior species. Recent studies provide evidence that they are, in fact, distinct species: Dolly Varden is more closely related to Arctic Char (Salvelinus alpinus), while Bull Trout is more closely related to an Asiatic species, the White-spotted Char (Salvelinus leucomaenis) (Cannings and Ptolemy 1998). Many Bull Trout and Dolly Varden populations overlap, and intermediate hybrids have been identified (Baxter et al. 1997). Generally, Bull Trout adults are large (up to 103 cm, 14.5 kg), piscivorus interior species that make seasonal migrations from large lakes into tributaries to spawn; although up to four life-history patterns have been identified, including a dwarf headwater stream variety (Cannings and Ptolemy 1998). Dolly Varden is a small coastal species with sea-run and non-migratory populations.

Spawning occurs during the fall when water temperature reaches about 9° C. A redd is prepared in large, clean gravel by the female. Aggressive males court a female by quivering alongside her as she rests over the nest. Occasionally, precocious satellite males take advantage of their small size to sneak into the redd and deposit milt while the dominant pair are engaged in the spawning act.

Bull Trout are highly susceptible to habitat degradation and displacement by introduced salmonid species, especially Lake Trout (Salvelinus nammycush) and Brook Trout (Salvelinus fontinalis). Bull Trout are presently the only fish species currently recognized by the British Columbia Forest Practices code.

In the Columbia system, Bull Trout inhabit lakes and streams that are less than 15° C throughout the upper and lower Columbia, upper and lower Kootenay and Flathead systems. Bull Trout have a block-shaped head with a large mouth, the upper jaw extends past the hind margin of the eye in adults. The dorsal fin is dusky without clearly pigmented or black markings. The anal and pelvic fins have a cream-coloured leading edge.

Comment on Whitefish (Prosopium)

This understudied genus is distributed throughout Siberia and western North America. Prosopium houses six distinct species worldwide, and two are native to the Columbia Basin. The fossil record suggests that Mountain Whitefish (P. williamsoni) is the least derived and ancient member of the genus prosopium, and probably has its evolutionary roots in western North America rather than in Siberia (Norden 1970). As a group, the whitefish are a notoriously phenotypically variable family that successfully inhabit cooler lakes, rivers and streams. They are generally fall spawners and perform complex seasonal reproductive and foraging migrations (Northcote and Ennis 1994).

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Prosopium coulteri (Eigenmann and Eigenmann)	Pygmy Whitefish
Prosopium=a mask, from the large bones in the front of the eyes coulteri=after Dr J.M. Coulter, a distinguished botanist

Pygmy Whitefish are abundant in lakes, rivers and streams of near mountainous areas. The species was first described in 1892 from the Kickinghorse River near Field, B.C. (McPhail and Lindsey 1970). The current western North American distribution ranges along the Continental Divide from southern Alaska to Montana. In 1952, Pygmy Whitefish were shown to have a disjuct distribution in North America when they were discovered in a trawl catch in Lake Superior (Scott and Crossman 1973). This discontinuous distribution suggests that Pygmy Whitefish took advantage of a series of large pro-glacial lakes that were formed through central Canada after the last glacial retreat approximately 10,000 BP (Johnston 1946; Stewart and Lindsey 1983). It is likely that there will be further discoveries of Pygmy Whitefish across the Central Plains as more surveys are conducted. In addition to having a discontinuous distribution, some Pygmy Whitefish populations in lakes contain two forms -- one form resembles the default form and is typically small -- the other is several times larger and is commonly known as Giant Pygmy Whitefish.

In the Columbia Basin Pygmy Whitefish is restricted to the cool lakes and rivers of the upper and lower Columbia and Kootenay systems, as well as to the major lakes of the Okanagan system.

Pygmy Whitefish can be identified by its blunt snout, rounded cigar-shaped body, large scales and adipose fin. Although there have been reports of Pygmy Whitefish of up to 27 cm in length, it generally averages 10-13 cm long.

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Prosopium williamsoni (Girard)	Mountain Whitefish
Prosopium=a mask; from the large bones in the front of the eyes williamsoni=after Lt R.S. Williamson of the U.S. Pacific Railroad exploration

The Mountain Whitefish is indigenous to interior lakes, rivers and streams of western North America, including all regions of British Columbia. Although the Mountain Whitefish is not an esteemed sportfish, it is often pursued by anglers for its troutlike behaviours and sweet-tasting flesh.

Recent evidence suggests that there are at least two forms of Mountain Whitefish in the rivers of British Columbia -- a long-snout and a short-snout variety. The long-snout morph is characteristically found in riverine habitats, and has an elongate, upturned snout used to overturn rocks and dig into crevices along the river bottom. The blunt short-snout form picks drift suspended in the water column and avoids foraging along the bottom (Troffe 1999a). The two fluvial forms of Mountain Whitefish are known from the Fraser, Peace and Columbia systems, and there is evidence suggesting that the forms are genetically distinct. The long-snout 'Pinocchio' form of fluvial Mountain Whitefish resembles the Chisel Mouth Jack (Prosopium oregonium) originally described from Oregon State in 1909 (Jordan and Snyder 1909).

Mountain Whitefish usually mature when they are three to four years old. Little is published about the reproductive behaviour of Mountain Whitefish; however, spawning takes place during the fall over unprepared gravel when water temperatures reach 5-7°C (Hagen 1970; Troffe pers. obs.). Breeding fish aggregate in step-off riffles in rivers or along gravelly margins in lakes. Early reports have suggested that spawning is a nocturnal activity (Brown 1952). Eggs hatch in the early spring, and juveniles can be found along the edge and backwaters for several weeks after hatching before moving into deeper water.

Mountain Whitefish are common and distributed throughout the Columbia Basin except above barriers in the Similkameen system.

Mountain Whitefish are troutlike in their appearance, have a small mouth without teeth, large scales and a prominent adipose fin. Juveniles have 8-10 neatly arranged parr marks along the lateral line.