Mike Cline, Bozeman, Montana

Although there are several species of whitefish found in the U.S., the Mountain Whitefish (Prosopium williamsoni) is probably the only one that would be considered a fly rod fish. They are decidedly difficult to catch (unless you are fishing with bead head nymphs, throwing small dry flies or stripping small woolly buggers or soft hackles.) This is a fish of the northern Rockies, thus it is often called the Rocky Mountain Whitefish. It is one of five Prosopium whitefish found in the northern Rockies, but by far the most prolific and probably the only one that is actively targeted by fly fishermen. Many folks don’t realize that the whitefish is a Salmonid and a very close relative to our favorite species of trout and grayling. This is a fish of cold water rivers and lakes, something we are blessed with in abundance out in the Northwest. Just about any good sized river suitable for trout will hold a population of whitefish.

19-20 Whitefish on Woolly Bugger
19-20 Whitefish on Woolly Bugger

Here in SW Montana, all our major rivers have healthy populations of mountain whitefish and some biologists consider the whitefish an indicator of overall stream health. The Montana Department of Fish, Wildlife and Parks have recorded whitefish populations as high as 15,000 per mile in some of our larger rivers. Unfortunately, some rivers such as the Madison are seeing a decline in whitefish populations. The typical whitefish is going to be 10-12”, but larger fish aren’t that uncommon. The Montana state record is 23” at 5.1 lbs. Having caught a number of 19-20” whitefish, I can say with all honesty that they are a worthy opponent at that size. If you find yourself catching average size whitefish along the edge of a run, try and get your flies a bit deeper and farther out in the channel, that’s where the larger fish lie. No matter what size whitefish you connect with, they are good eating as well with a mild, white flesh akin to walleye if bleed and iced quickly.

I am confident that many visiting anglers, especially those that make only one trip per year to trout fish in Montana’s rivers, don’t like whitefish. They are seen as a pest. They won’t leave those small nymphs alone. This is especially so for those floaters who like to fish nymphs under indicators a few feet from the bank. It’s where the trout are because there’s cover and food, but it’s also where the whitefish are. They are indeed bottom feeders that relish small caddis larvae, stonefly and mayfly nymphs, so any typical small nymph pattern, especially those bead heads, is going to attract strikes. On the Yellowstone or Big Hole along the edges of runs 3-6 feet deep, in fast tail outs or at the head of big riffles, drift a nymph under and indicator and you are most likely to catch a whitefish.

A Mug to Save the Day
A Mug to Save the Day

However, there are several approaches to catching whitefish that can prove challenging and will ultimately improve your skills. The first challenge involves just removing that indicator from your leader and dead drifting those nymphs through the runs. With floating line or sink tips, whitefish takes are still subtle and it will take concentration on your part to get hookups. If you can consistently catch whitefish without an indicator that same concentration and skill will help you fish bigger nymphs without indicators for trout. Going light with rod and leader and using barbless hooks will also make catching whitefish more fun. Next time you are on a river where catching whitefish is routine, take along the three weight, preferably glass but light graphite is just as fun. Push those tippets down to 5 and 6X. If wind is not an issue the lighter rod and leader will prove exciting when you connect with one of those larger whitefish. Whenever you find yourself on a river and there’s some sort of hatch going on with tiny insects, you are likely to find prolific rises from whitefish in the tail outs of pools. This is especially true of midge hatches in the Spring and Tricos in summer. They will gather in droves in shallow tail outs and rises everywhere will signal their presence. These are relatively difficult fish to catch on a dry fly. It’s not that they are selective, but rather they aren’t entirely stupid either. In fast tail outs, approach and presentation are important. Whitefish recognize a dragging fly as well as any trout. Fortunately, they are not put down as easy as trout, so dry fly fishing for whitefish amidst a prolific hatch is just plain good practice. Combine that with a light rod and leader and you can have a good ole time.

Probably few anglers, if any, travel out west to target whitefish. But once you are here, this prolific fish can save the day and provide you with some interesting angling challenges should you choose to give them a try.

3 Comments

  1. Very interesting article Mike. If Mountain Whitefish occupy the same water as do trout, eat the same subaquatic fare, and are as voracious as trout but appear less put off by disturbances, they may come to take the lion’s share of the grub. Do they out-compete their more famous cousins? Do they tend to slowly “take over” water where they’re both established?

    If not, what factors might limit them? Are they perhaps less well adapted to temperature extremes, or slower to multiply, or maybe less able to feed on trout fry as well as trout feed on their own fry?

    WOndering what keeps the balance. I’ve seen species edge out other species before. Mountain Whitefish sound like the kind of fish that has the collective ability to do that. But I know very little about them.

    – Mike Vorhis

  2. Mike,
    First of all, mountain whitefish are natives and as far as I know, haven’t been introduced anywhere outside their native range. So they evolved and coexisted with other natives in the same rivers—Coastal, Westslope, Yellowstone and Snake River cutthroat, coastal and Columbia redband rainbow trout and grayling for centuries. The introduction of rainbows and browns into Rocky Mountain rivers adversely impacted the cutthroats and grayling but apparently not the Whitefish. They seem to do just fine with Rainbows and Browns and what remains of the Yellowstone cutthroat.

    Most of our rivers are so rich in aquatic insects and bait fish that I don’t think sufficient food for all species is an issue. Throughout the season whitefish are considered bottom feeders focusing on insects and other food close to the bottom, whereas trout typically focus on insects in the flow higher in the water column. Of course that is a generalization that helps the angler very little as both species will rise to hatching flies.

    They do spawn at the same time as brown trout but in different parts of the river. Of course rainbows and cutthroats are spring spawners and typically move into tributary creeks in early spring. Whitefish and Browns are late fall spawners. Browns spawn both in the main rivers and tributaries in Oct-Nov in shallow, fast moving water over heavy cobble in redds whereas whitefish are broadcast spawners in deep mid river over fine gravel and cobble. Whitefish fry are a good spring food source for trout.

    I think the most important thing to remember about Mountain Whitefish is their need for clean, unpolluted cold, deep water. Whereas rainbows and browns are far more tolerant of degraded water, whitefish aren’t. Their presence is the sign of a healthy river system.

    Mike Cline
    Bozeman, Montana

  3. Fascinating; thanks for the education. We tend to think of trout as representing the pinnacle of habitat purity…and yet a fish that no one seems to worship (maybe only because the mouth shape reminds them of fish that thrive in warm murky waters) decisively eclipses the noble salmonids in that respect.

    And…now that you mentipon it, I do recall learning, even back in the midwest years ago, that although the uninitiated would confuse suckers with carp, in fact suckers were disappearing and only populated very clean streams and healthy systems. The two species were very different. Few if any ever targeted them in their quest for bass, as the sucker’s mouth shape branded them “scavengers,” but now I wonder if it wasn’t a similar scenario to what you describe with Mountain Whitefish in the High Lonesome.

    – Mike

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