Rocky Mountain Whitefish

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.

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