Mountain Whitefish
Prosopium williamsoni
Mountain whitefish are slender, silvery salmon-family fish with a deeply forked tail and a small mouth beneath an overhanging snout. Native to western North America, they live in cold rivers and also occur in lakes and reservoirs. They feed mainly on aquatic insects, often taking food near the bottom, and gather to spawn over gravel in autumn. They are distinct from lake whitefish.
Cold mountain rivers and streams, plus some lakes and reservoirs; gravel and small-rubble areas provide spawning habitat.
Image credit and sources
Mountain whitefish underwater. Resized/recompressed for the site; this image and its variants remain CC BY-SA 4.0.
Image: Brian Varner (Fishinphoto) — CC BY-SA 4.0
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Species information reviewed 2026-10-16.
Mountain Whitefish Habitat & Size
Mountain Whitefish (Prosopium williamsoni) is associated with river water and lake water in the species record. Habitat information describes the species, not permission to fish for it. The recorded average size is approximately 12 inches; individual sizes vary.
Recorded Waters for Mountain Whitefish
Outland Atlas links Mountain Whitefish to water records in Alaska, Alberta, British Columbia, Idaho, Montana, Nevada, Oregon, Utah, Washington, and Wyoming. These associations may reflect documented presence, seasonal runs, or historical stocking, not angler catch reports or current abundance. Read the linked water guides and source notes for evidence dates and reaches.
Mountain Whitefish Fishing Regulations & Limits
A recorded association does not establish that targeting or retaining Mountain Whitefish is permitted. Confirm current species protections, seasonal and emergency closures, reach-specific rules, gear restrictions, bag and size limits with the responsible fisheries authority before fishing. A fishing license does not override these restrictions. Outland Atlas's regulation records may be incomplete; missing rules do not mean unrestricted fishing.
Related Water Guides for Mountain Whitefish
Explore these Outland Atlas water guides for places where Mountain Whitefish is recorded:
- Yellowstone River — recorded Mountain Whitefish association
- Bow River — recorded Mountain Whitefish association
- Kootenay Lake — recorded Mountain Whitefish association
- Arrow Lakes — recorded Mountain Whitefish association
- Elk River — recorded Mountain Whitefish association
- St. Mary River — recorded Mountain Whitefish association
- Quesnel Lake — recorded Mountain Whitefish association
- Stuart Lake — recorded Mountain Whitefish association
- Nechako River — recorded Mountain Whitefish association
- Williston Lake — recorded Mountain Whitefish association
- Peace River — recorded Mountain Whitefish association
- Oldman River — recorded Mountain Whitefish association
- Crowsnest River — recorded Mountain Whitefish association
- Upper Kananaskis Lake — recorded Mountain Whitefish association
- Abraham Lake — recorded Mountain Whitefish association
- Ram River — recorded Mountain Whitefish association
- Clearwater River — recorded Mountain Whitefish association
- Athabasca River — recorded Mountain Whitefish association
- McLeod River — recorded Mountain Whitefish association
- Pembina River — recorded Mountain Whitefish association
- Smoky River — recorded Mountain Whitefish association
- Wapiti River — recorded Mountain Whitefish association
- North Saskatchewan River — recorded Mountain Whitefish association
- Peace River (Alberta) — recorded Mountain Whitefish association
- Delta Clearwater River — recorded Mountain Whitefish association
- St. Joe River — recorded Mountain Whitefish association
- Bear Lake — recorded Mountain Whitefish association
- Blackfoot River — recorded Mountain Whitefish association
- Flathead River — recorded Mountain Whitefish association
- Kootenai River — recorded Mountain Whitefish association
- Lake Koocanusa — recorded Mountain Whitefish association
- Hungry Horse Reservoir — recorded Mountain Whitefish association
- Bitterroot River — recorded Mountain Whitefish association
- Clark Fork River — recorded Mountain Whitefish association
- Blackfoot River — recorded Mountain Whitefish association
- Rock Creek (near Missoula) — recorded Mountain Whitefish association
- Beaverhead River — recorded Mountain Whitefish association
- Big Hole River — recorded Mountain Whitefish association
- Madison River — recorded Mountain Whitefish association
- Missouri River (Montana) — recorded Mountain Whitefish association
- Gallatin River — recorded Mountain Whitefish association
- Jefferson River — recorded Mountain Whitefish association
- Ruby River — recorded Mountain Whitefish association
- Smith River — recorded Mountain Whitefish association
- Truckee River — recorded Mountain Whitefish association
- East Walker River — recorded Mountain Whitefish association
- Jarbidge River — recorded Mountain Whitefish association
- Deschutes River — recorded Mountain Whitefish association
- Metolius River — recorded Mountain Whitefish association
- Crooked River — recorded Mountain Whitefish association
- Grande Ronde River — recorded Mountain Whitefish association
- Provo River — recorded Mountain Whitefish association
- Logan River — recorded Mountain Whitefish association
- Weber River — recorded Mountain Whitefish association
- Blacksmith Fork River — recorded Mountain Whitefish association
- Yakima River — recorded Mountain Whitefish association
- Green River (Wyoming) — recorded Mountain Whitefish association
Equipment planning for Mountain Whitefish
We have not selected a species-specific affiliate setup for this guide. First establish whether targeting is permitted at your destination; no tackle recommendation should be inferred from a species record.
A closed season prohibits targeting, even with release. Follow the water-specific rules linked in this guide.
- Check permitted methods, bait and hook restrictions before choosing tackle. Match rod, line and lure ratings to the lawful method and conditions, rather than buying by species name alone.
- Plan weather protection, drinking water and a way to call for help. For boat trips, confirm required flotation and safety equipment with the responsible boating authority.
- Read the habitat and water-specific source notes in this guide, then confirm an appropriate lawful method with the local fisheries authority before choosing equipment. Do not assume a general freshwater combo suits every species or water.
This is an editorial planning checklist, not hands-on product testing. Use equipment you already own when suitable. The gear directory contains affiliate links; any product suggestions below have their own disclosure. Retailer region, availability and Canadian shipping are not guaranteed.
Browse the gear directory · Find official fishing-rule sources · Affiliate disclosure
Mountain Whitefish Regulations
Review available regulation records and confirm whether fishing for Mountain Whitefish is permitted with the responsible fisheries authority:
Frequently Asked Questions
What water types are associated with Mountain Whitefish?
The species record associates Mountain Whitefish (Prosopium williamsoni) with river water and lake water. Habitat information is not evidence of current abundance or permission to target the species.
How big does Mountain Whitefish get?
The recorded average size for Mountain Whitefish is approximately 12 inches. Individual sizes vary; this average is not a maximum size or a legal retention limit.
Where does Outland Atlas record water associations for Mountain Whitefish?
Outland Atlas links Mountain Whitefish to water records in Alaska, Alberta, British Columbia, Idaho, Montana, Nevada, Oregon, Utah, Washington, and Wyoming. These associations may reflect documented presence, seasonal runs, or historical stocking, not angler catch reports. Check the linked water guides and source notes for evidence dates and reaches; a listing does not guarantee current presence or legal fishing opportunity.
Does a listing or fishing license permit fishing for Mountain Whitefish?
No. A listing records an association, not permission to target or retain Mountain Whitefish. License requirements and exemptions vary. Confirm current species protections, seasonal and emergency closures, reach-specific rules, gear restrictions, bag and size limits with the responsible fisheries authority. A license does not override restrictions, and missing Outland Atlas regulation records do not mean unrestricted fishing.