Pleistocene Whitefish (Coregonus clupeaformis)

Fish have an amazing ability to replenish and increase their populations. Lake whitefish, a species related to salmon and trout, can lay between 8,000-130,000 eggs. During Ice Ages 90% of their present day range was covered by glaciers, making it uninhabitable for them. Yet, in less than 12,000 years they recolonized this enormous territory. The reproductive ability of this species outpaced the population of predatory fish and birds that fed upon them. Scientists used a study of genetics to determine modern day whitefish descend from 2 different refugial populations that clung to survival during the Last Glacial Maximum. 1 population survived in Beringia–the area of Alaska and the Yukon that remained free of glacial ice. They may have survived in lakes now located near Nahanni National Park. The other population occurred in the Missouri/Mississippi River Drainage just south of the Laurentide Ice Sheet. Following the retreat of the Ice Sheet, lake whitefish populations exploded in the newly formed Great Lakes and managed to swim their way into lakes all over Canada. Whitefish are a cold water species and probably didn’t ever live far from Ice Age glaciers.

Map of present day range of lake whitfish. Most of this range was under glacial ice during Ice ages.
Lake whitfish.

Lake whitefish average 4 lbs. as adults, though the record for a rod and reel catch is 15.5 lbs. They spawn during fall, winter, and spring. Their diet consists of snails, clams, and insects. There are 2 ecotypes of whitefish that do not interbreed: the normal population that inhabits the bottom region of lakes and the dwarf population that swims in the upper layer of open water. Commercial fishermen net whitefish, and they are a popular food fish in cities and towns along the Great Lakes, but I can’t remember if I ever had the opportunity to try them when I lived in Ohio as a boy.

Reference:

Foote, C.; J. Clayton, C. Lyndsay, and R. Bodaly

“Evolution of Lake Whitefish (Coregonus clupeaformis) in North America during the Pleistocene: Evidence for a Nahanni Glacial Refuge in the northern Cordilleran Region”

Canadian Journal of Fisheries and Aquatic Services 49(4) April 2011

McDermid, J., J. Riest, R. Bodaly

“Phylogeography and Post Glacial Dispersal of Whitefish ( C. clupeaformis complex) in Northwest North America”

Advances in Limnology 60 Jan 2007

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