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

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Lake Chub
Couesius plumbeus

What do they look like?

A moderate sized (adults usually less than 100 mm in fork length) minnow, usually with a dusky mid-lateral band and a large terminal mouth (typically the upper jaw reaches back to the anterior margin of the eye) and, when viewed from below, maxillary barbels are clearly visible just forward of the corners of the mouth.

Where do they live?

Although lake chub are an abundant and widespread species in B.C., almost no quantitative data is available on their habitat use. Consequently, the following account draws heavily on data from outside the province. There is, however, some data from Dina Lake #1 in the upper Peace system.

Adult lake chub occurs in a wide variety of habitats. At the southern edge of the B.C. distribution it is primarily a lacustrine species, but over most of the province it occurs in everything from the mainstems of large rivers to tiny streams, and in standing water. There is some evidence that, in the northern parts of their range, lake chub are migratory. They move from large rivers into tributary streams in the spring and migrate back to large rivers in the fall. Presumably, the spring in-migration is to spawning and summer foraging sites while the fall out-migration is to over-wintering sites.

In Dina Lake #1, in the spring, adult lake chub occur throughout the littoral zone at depths ranging from about 0.5 to 10 m. By late June adults move closer to shore and, during the day, small schools are common in shallow water where large numbers were observed sheltering in the tangled branches of fallen spruce trees. At night, however, they dispersed away from shelter sites and individual adults were commonly seen 50 or more meters offshore.

Basically, juvenile (1+) lake chub use the same habitats as adults. During the day in Dina Lake #1 they were strongly associated with cover and aggregated among the branches of fallen spruce trees. At night, however, individual fish spread out into exposed littoral areas. In the late spring, in Dina Lake #1, young-of-the-year lake chub were concentrated within a metre of shore in water less than 1 m deep. They were also observed in mid-water over a variety of substrates (sand, organic litter, and fine gravel) but appeared to avoid exposed areas with coarse gravel and cobble bottoms. Cover seemed important and most individuals were associated with weeds or the branches of trees that had fallen into the lake. At this time, most of the under yearling chub were solitary or loosely associated with two or three other individuals. As the summer progressed the young-of-the-year chub formed small schools and ventured 2 or 3 m from shore. By October they had joined the juvenile population.

What is their life like?

There is relatively little information on the life history of lake chub in British Columbia. At some northern sites, lake chub spawn shortly after ice-out. Farther south, spawning typically peaks in July and continues into late August. In the upper Peace, breeding occurs throughout June. Apparently, spawning is temperature dependent (4 to 10 °C) and the peak can vary by two or three weeks.

Lake chub tend to spawn more than once (fractional spawners) and, although fecundity varies with female size (500-2,400 eggs), not all eggs are released at a single spawning. By late July, in the Clinton area, young-of-the-year average about 20 mm in fork length (16-24 mm), and by the end of the growing season (early November) the cohort has an average fork length of about 30 mm (28-34 mm). Sexual maturity probably is achieved at either the end of the second, or the beginning of the third, summer of life.

What do they eat?

The diet of lake chub primarily consist of benthic organisms (e.g., amphipods, chironomid larvae, oligochaetes, and some plant material) but they also take terrestrial insects and occasionally the fry of suckers and minnows. Lake chub associated with the Liard Hotsprings forage primarily on Chara. This species appears to be cold adapted, and fish collected in October from Kledo Creek near Fort Nelson were still actively foraging at water temperatures of 1.2 °C.

What is their distribution? The lake chub is one of the most widely distributed minnows in North America. In the east, they range from northern Quebec south to the upper Delaware River and, on the Great Plains from the Mackenzie Delta to Colorado. West of the Continental Divide, lake chub are found from the middle Yukon system south to the glaciated portions of the Columbia system. In British Columbia, lake chub are an inland species - abundant throughout the upper Fraser and upper Skeena systems but absent from roughly the lower hundred kilometres of these rivers. Similarly, they are present in the upper reaches of many coastal rivers, especially those that rise on the Interior Plateau but are absent in the lower reaches of these same rivers. At the southern end of their B.C. range (the Columbia system), the distribution is fragmented into scattered, isolated populations but, on the Interior Plateau and in the northeastern portion of the province, lake chub are ubiquitous.

View Peace Williston distribution map.