Biology Bits with Joe McMullen

Good Stream Flows Help Fend Off Winter Damage

Winter has a pronounced affect on the next fishing season, and last winter was one that should have a very positive impact. The strong flows of last summer and fall continued through the winter, eliminating three types of ice formations that occurred during the winter of 2002¬2003. The good stream flows enable the spring water, which emerges from the ground at 50 degrees, to travel down the valley quickly enough so that the cold air temperatures we experienced last winter did not chill the water enough to cause flow ice, surface ice, or anchor ice to form.

Flow ice and surface ice form when the creek temperature drops into the lower 30-degree range, causing the surface to begin to freeze in slower areas. The flow ice forms and then moves along with the stream flow; it is constantly pushed under the surface, causing stream temperatures to drop still lower. Surface ice simply covers the slower flows of the stream, and like flow ice, it also causes depressed surface temperatures. Stream temperatures lowered by ice have a major impact on trout metabolism, which reduces winter growth. Last winter saw fish feeding nearly every day, thus stronger and larger fish for the coming season.

Anchor ice is a completely different situation. It is one of the most devastating natural phenomena that can occur in a stream. Anchor ice forms on the bottom of a creek and seals the streambed. This kills many of the organisms dwelling there by freezing or lack of oxygen. The summer of 2002 produced such low flows that anchor ice was common durng the 2002¬2003 winter in many of our beats on Spruce Creek. At least some of the blame for the sparser insect hatches last season could be traced to the great amount of anchor ice. Last winter, we escaped this problem completely, which should be great for the coming season.

Another positive aspect of last winter was the snow accumulation should ensure a steady spring runoff and good stream flows throughout the spring. That is always a good thing for both fish and bugs. All things considered, it was a very good winter.

As a closing note, our new sections on Yellow Creek seem to have an abundance of invertebrate life. We haven¹t had good enough weather to get a real in-depth look, but what I have seen, I like! I am looking forward to working with and fishing on these waters. They will be a real asset.

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