Montana Water Center - aquatic sciences lab

Aquatic Sciences Laboratory - Species Profiles

Mountain Whitefish
Prosopium willamsoni

Mountain whitefish are native to the waters of Montana. While many anglers consider them unworthy of their time, whitefish are considered worthy gamefish that can be caught throughout the winter and taste good. Mountain whitefish have a wide distribution, in part because of their ability to tolerate warmer and more turbid waters than other native salmonids such as grayling or cutthroat trout.

Mountain whitefish spawning behavior is similar to that of lake trout and grayling. Instead of digging redds (nests), males fertilize the eggs of females that are released over selected rocky substrates, mainly in streams, but some lake-dwelling populations are known to spawn in the lake or both habitats. In general, spawning occurs during October and November, but has been known to extend to January and February in lakes, with fry hatching in March and April.

The largest threat to mountain whitefish populations is overexploitation by fishing. Most individuals become sexually mature at 3 years and approximately 11 inches, and the largest individuals of 12-16 inches are likely 5-8 years of age. Due to this biological consideration, restrictive regulations may have to be imposed to protect some populations from overexploitation.

References:

Brown, C.J.D. 1971. Fishes of Montana. Big Sky Books, Bozeman, MT.
Behnke, R.J. 2002. Trout and Salmon of North America. The Free Press, New York.

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