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
Pygmy whitefish, late November-December
Cisco, late November-early December
Kokanee, lake trout, late October-November
