I can’t hear Franz Schubert’s "Trout" Quintet without thinking about the spring fish runs in the tributaries of Lake Michigan. Actually, our native trout are more likely to spawn in the fall, but rainbow trout join fishes such as pike and suckers this time of year.
As with any migration, fish leave the big lake to swim upstream because tributaries provide the optimal breeding habitat. Trout and suckers prefer gravel-bottom streams, while pike brazenly push into warm, shallow areas with emergent vegetation.
For spawning and for their developing young, streams offer huge survival benefits. But in a very real way, the fish also contribute to the health of the streams they favor.
Fish transfer nutrients — nitrogen and phosphorus — from the lake into the stream in the form of eggs and milt, as well as through their excrement.
Through their foraging and energetic spawning behavior, they stir up nutrients from the sediment into the water, making them available to aquatic vegetation — the foundation of the stream’s food web. Speaking of the food web, other wildlife also feed on the eggs, fry, and breeding fish, further integrating these seasonal migrations into the ecosystem.
Fish benefit greatly from the tributaries, but they also give back, enriching the very ecosystems that sustain them.
It’s sort of like Interlochen Public Radio. Those who benefit from its broadcasts and online services understand that their contributions are necessary for the health and longevity of IPR.
