Did You Know? (December 2008)

Westslope TU chapter president, Mike Willett, with a winter rainbow from Montana's Bitterroot River.

What do trout do in the winter?

As winter sets in, water temperatures approach freezing and trout metabolism consequently slows down. Adult trout migrate to deeper pools and smaller trout often burrow into open spaces among rocks in riffles. As rushing water becomes supercooled by frigid air temperatures, a type of ice called frazil ice can form along the stream bed and form a slush that can suffocate young trout. Streams and rivers that are wider and shallower are more prone to frazil ice.