Whitefish

Whitefish, represented here by the lake whitefish (Coregonus clupeaformis), are a group of coldwater fish in the genus Coregonus, part of the salmon family Salmonidae along with trout, char, and grayling. They are widespread across cold, deep lakes and some rivers of North America and, in related species, across northern Europe and Asia. Whitefish have long supported major inland fisheries throughout their range. They are generally silvery, streamlined fish adapted to open-water and deep, cold habitats, distinguishing them from the more colorful trout and salmon in the same family. Numerous closely related coregonid species exist, often difficult to distinguish without close examination.

Whitefish are identified by their plain silvery coloration and small head relative to trout:

• Slender, laterally compressed body, silvery white on the sides with an olive-gray to bluish back
• Small, pointed head with a small, subterminal (underslung) mouth adapted for bottom feeding
• Large, easily visible scales compared to trout or char
• Deeply forked tail and a small adipose fin present, similar to other salmonids
• Lacks the dark spots, red markings, or vermiculations seen in trout and char, giving it a plain, uniform appearance

Lake whitefish inhabit cold, deep, well-oxygenated lakes across northern North America, including the Great Lakes, Canadian lakes, and parts of Alaska, with related coregonid species found in cold lakes and rivers of northern Europe and Asia. They generally prefer deeper water than trout, often residing near the bottom in depths of 20-60 meters during warmer months, and moving to shallower water in fall to spawn. Whitefish require clean, oxygen-rich, cold water and are sensitive indicators of lake water quality. Some populations also inhabit large, cold rivers, but lakes remain their primary environment throughout most of the year.

Whitefish are schooling fish that move in loose to dense groups, particularly while feeding along lake bottoms or suspended over deep water. They feed primarily on bottom-dwelling invertebrates such as insect larvae, small crustaceans, and mollusks, using their downward-facing mouths to forage along sediment. Spawning occurs in autumn or early winter, when adults move into shallow, gravelly nearshore areas or river mouths to broadcast eggs over the substrate without building nests. Whitefish play an important ecological role as both predator of small invertebrates and prey for larger fish, making them a key link in cold-lake food webs.