Mountain Whitefish Fishing Guide

The mountain whitefish (Prosopium williamsoni) is the most abundant salmonid in many Rocky Mountain river systems, often present in far greater numbers than the trout species that attract most angler attention. It occupies the same cold, clear, swift rivers as trout — and in many drainages is the ecological equivalent: long-lived, invertebrate-feeding, and highly sensitive to water quality degradation. Mountain whitefish have a cylindrical body, small subterminal mouth, and large scales that distinguish them from trout, which they otherwise share waters with throughout the intermountain West. They are underrated as a sport fish: they take dry flies, nymphs, and small spinners, fight with a strong, head-shaking run, and are excellent eating — their mild, white flesh deteriorates quickly after death and must be kept cold. Fly fishers targeting cutthroat and rainbow trout frequently encounter mountain whitefish and often dismiss them unfairly.

Mountain Whitefish is a freshwater species.

Habitat

Mountain whitefish inhabit cold, clear, swift rivers and streams of the Rocky Mountain West from British Columbia and Alberta south to Utah and Nevada, as well as some deep cold-water lakes in the region. They favor riffle and run habitats over gravel and cobble substrate, sharing water with cutthroat, rainbow, and brown trout. They require high water quality and dissolved oxygen.

Diet

Mountain whitefish feed almost entirely on aquatic invertebrates — mayfly, caddisfly, and stonefly nymphs form the core of their diet, supplemented by midges, worms, and small crustaceans. They feed in the water column and at the bottom, rising to surface insects less often than trout though they can be caught on dry flies during heavy hatches.

Fishing Techniques

Best Seasons

Fall, Winter, Spring

Size & Records

Average weight: 0.75 lbs. World record: 5.57 lbs (Elbow River, Alberta, Canada (1995)).