Species Profile: Mountain Whitefish

As most of you hopefully already know, I am a life-list angler. I target, document, and count the number of species, hybrids, and subspecies I catch, specifically on fly tackle. Because of that I spend a lot of time learning about and fishing for many different species of fish. This means I'm more adept at identifying and fishing for an extremely broad range of species than the average fly angler. This series will attempt to outline species identification, some life history, and methods for targeting with fly tackle. Maybe I'll get to every fish on my life list, but considering it is ever growing... it would take a while. Mostly, I hope this will get a few of you interested in going out and learning about or catching something new. 

There is a fish that lives in the Mountain West, a salmonid with chrome flanks and gentle appearance. This fish feeds mostly on insects and small crustaceans and worms, and does sometimes rise to hatches. Not only is it good sport but it is fine table fare. Most fly fisherman who have fished  for this elegant native fish speak very highly of it....
I'm kidding about that last part, the species I'm talking about today is the mountain whitefish, Prosopium williamsoni, and actually a lot of fly fisherman would be perfectly happy to never catch a mountain whitefish. I, of course, am not one of those types, so let's dive in and learn about the small-finned grayling itself, the fallfish of Montana, and try to discern what exactly it is that makes them unlikable (spoiler alert: there's no real legitimate reason they're so disliked).

Prosopium williamsoni

Mountain whitefish are found in cold, clean rivers and some lakes from the Mackenzie River drainage, non-coastal BC, and east slope of the Rockies in Alberta and Montana, most of Washington, Oregon, and Idaho, extreme northern Nevada, Northern Utah, and Northwestern Colorado. There is also a small pocket of mountain whitefish persisting in the Truckee River drainage in California.
Whitefish have much the same sort of habitat requirements as most other salmonids, cold, clean, well oxygenated water with healthy macroinvertebrate populations are necessary to sustain a population. Their overall body shape and fin arrangement is very trout like, but their slightly larger silvery scales and odd shaped face make them appear more like a cyprinid. The upper jaw of the mountain whitefish is much longer than their lower jaw, and looks sort of like a long shovel nose. This snout distinguishes them from other similar species, like cisco and lake whitefish. Mountain whitefish use their snout and pectoral fins to root in the bottom for food items.

A stretch of river in Montana home to numerous mountain whitefish.

Mountain whitefish have a white belly, silvery flanks with olive undertones, and an olive grey back. Their operculum often has a lavender or maroon coloration or iridescence. Adults average between 10 and 16 inches but can grow substantially larger than that, well into the high 20 inch range. They may live 16 years or more. Mountain whitefish spawn in from September through December, depending where in their range they are and seasonal weather trends. Like trout, they cut redds in gravel or small cobble and deposit eggs so they fall into the species between the stones. Eggs hatch in late winter and early spring.

Throughout their range, mountain whitefish are an important forage fish for large predatory fish species both native and non-native, as well as birds of prey and some mammals. Historically, they have been an important food fish and game fish.

In 2016, low and warm waters in southern Montana, conditions tied to anthropogenic climate change, facilitated the spread of a parasite, Tetracapsuloides bryosalmonae. This parasite infected cutthroat, rainbow trout, longnose suckers, sculpins, and dace, but mountain whitefish were especially prone. Massive fish kills hit the Yellowstone River in particular hard, where fish already at risk of mortality from excessively warm waters succumbed to the parasite. Montana FWP temporarily shut down the Yellowstone River to all recreational activities. The impacts of the fish kill were still evident when I fished the area in late 2018. Whitefish numbers were exceptionally diminished.

The Yellowstone

Tactics for catching mountain whitefish on the fly are basically the same as for trout, though there is almost no piscivorous aspect to their feeding, so there is no sense in fishing for them with streamers. Indicator and tightline nymphing, wet flies, and, when schools of whitefish are rising, dry fly fishing, will catch many hard fighting, beautiful whitefish. I found the handful of mountain whitefish I caught while nymphing in Montana to be great fighters for their size and a welcome change of pace from the trout, really weren't any harder to fool. 

Really, the prejudices against whitefish held by a lot of fisherman today hearken back to the same sort of "trash fish" mentality that persists in any place people fish. Though "trash fish" was intended originally to refer to the food quality of a fish, it is now used to describe a plethora of wild fish with no regard to their natural importance or sporting qualities. Before whitefish were considered the undesirable species they are in the west today, it was bull trout. Bull trout were intentionally killed in huge number throughout their range, and exist now in highly diminished numbers. Though the prejudice against whitefish hasn't extended to that despicable level, it is harder to find voices advocating for the species than it is to find voices advocating for non-native brown trout, and that is unfortunate. 

The mountain whitefish is an odd but beautiful little salmonid, and long may it swim the rivers and lakes of the mountain west. 

Until next time,

Fish for the love of fish.

Fish for the love of places fish live.

Fish for you.

Thank you to my Patrons; Erin, David, John, Elizabeth, Brandon, Christopher, Shawn, Mike, Sara, Leo, and Franky for supporting this blog on Patreon.