Wednesday, November 13, 2013

Montana Fall Spawners

Ten Montana fish species spawn in the fall. Bull trout kick things off starting in mid-September; mountain, lake and pygmy whitefish spawn well into December. All of our fall spawners are salmonids, e.g. members of the trout/salmon tribe. According to FWP Fisheries Biologist, Jim Vashro, “I don’t know why but of all the fish families only salmonids spawn in fall. But I do know “ fall spawning can give those fish a competitive advantage over rainbow, cutthroat trout and Arctic grayling which spawn in spring. When eggs are laid in fall they incubate over winter in gravel and hatch one to two months earlier than eggs laid in spring. That gives those fry a chance to grow and outcompete spring spawned fry.”

The risk is eggs laid in fall must survive sometimes brutal winter conditions such as floods washing eggs away and shelf-ice freezing them out. Vashro speculates one reason no warm water species lay eggs in fall is warm-water fry eat plankton which is most abundant in warm weather; while salmonid fry eat insects which are plentiful year around.

Montana’s Fall Spawners

Bull trout, mid-September-early October
Brook/brown trout, Chinook salmon, October-November
Mountain whitefish, November-early December
Lake whitefish, October-December
Pygmy whitefish, late November-December
Cisco, late November-early December
Kokanee, lake trout, late October-November

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