April 10, 2010
By Matt Straw
Mary Savage admires the silver sides and pink highlights of another nice one. Marine olive backs and multiple black spots. Pristine — untouched by other hooks or commercial nets. Plump and sassy, fresh from big water, aiming to kick ass and take names all the way to the spawning gravel — if that's what it takes.
And that spawning gravel could be 50 miles away or more, far into the realm of balsam, cedar, thin water, and rivulets, in trackless stretches where few people go.
So we let her go. We always let her go on streams where natural reproduction occurs. Even when it's only a rumor.
Mary pops another, standing on the remnants of a harsh winter. Harsh winters can kill steelhead trout. Dr. Paul Seelbach participated in a study that revealed a direct correlation between the number of days with anchor ice and the survival of steelhead parr through the winter. Anchor ice forms along the bottom of a stream, locking up the invertebrate food supply. It forms in air temperatures below 0°F, which can super-chill rivers. I've taken water temperatures readings of 31°F on several occasions during the months of January and February, when air temperatures hovered near 0°F. Weather that cold manifests itself in ice floes forming on the surface (where water meets the super-chilled air) and anchor ice forming on bottom (where currents are slowest).
Seelbach proposed it's possible to determine the percentage of a year class that will survive the winter by counting the number of nights that dive to sub-zero temperatures. Up here, on the tributaries of Lake Superior, temperatures often plunge to minus 20°F during the coldest months of the year.
Which makes you thankful for the small fish. Let 'em go. Let 'em grow.
