by Jerry Burton, NMT President
From the October/November 2014 Newsletter
Ever wonder how trout in a small high elevation stream survive when in the winter temperatures are below zero for weeks at a time and three feet of snow cover the stream? Some don’t. Those that do have found a deep spot where the ice cannot reach the bottom.
Winter can be tough on trout in small high elevation streams. If the flow is not strong enough, the stream may freeze to the bottom and if the trout have not found a deep hole they die. While the water continues to flow, but it flows on top of the frozen stream. Because of this, like spawning sites, safe wintering sites are an important part of a trouts habitat. These sites may hold most of the trout in a reach of stream.
Being cold blooded, trout don’t need a lot of food in winter when the water temperatures are in the mid to high thirty’s. In fact, they only need to consume one 
percent of their body weight to maintain themselves. During the winter they mostly lay the bottom and wait for spring and warmer water.
In high elevation lakes that contain trout the fish face a different winter threat. Snow on the surface of the lake, if gets so deep that it blocks the sunlight, will cause the aquatic vegetation in the lake to die. As the dead vegetation decays it uses up the oxygen in the lake and the fish die.