Mountain Whitefish (Prosopium williamsoni)

Body Type & Identification: Silver with small scales, a small toothless mouth, and an adipose fin — clearly in the salmon family. Cylindrical body more rounded than trout. Olive-brown on the back fading to silver sides. Distinguished from trout by the small, underslung mouth. A cold-water schooling fish of clear mountain rivers in the western US.

Preferred Water Temperature: 45°F–60°F. A cold-water species found in the same clear, rocky rivers as Rainbow and Brown Trout. Most active in winter — excellent January and February fishing in many western rivers when other species are slow. Spawn in fall over gravel beds.

Habitat: Clear, cold rivers and streams of the Rocky Mountain region from British Columbia south to Utah and Nevada. Found in the same pools and riffles as trout — often in larger schools in deeper pools. An important winter fishery on Idaho, Montana, and Wyoming rivers when trout are less active.

Best Lures: Small nymphs on fly tackle are the top producers — the same nymph patterns used for trout catch whitefish. Small jigs (1/16 oz) produce in winter. Small beadhead flies under an indicator work well. They eagerly take dry flies during insect hatches.

Best Baits: Small worms and maggots are very effective. Salmon eggs produce consistent results in fall and winter. Small pieces of nightcrawler on tiny hooks produce in winter. Light tackle with small hooks and natural bait near bottom in river pools.

Top 5 Destinations: Snake River ID, Flathead River MT, Green River UT, Bitterroot River MT, Bear River UT/ID/WY.