The amount of snow that falls in Yellowstone during these cold months can help determine how healthy the Yellowstone fisheries will be over the next year. I like to look at an abundant snowpack as if it were a refrigerator that is holding an important resource; a biological legacy that will establish the physical condition of the park’s fish population.
That legacy begins as a snowflake, but by spring it will supply a torrent of water that will reshape the park’s streams and rivers. Fast moving waterways push sediments and gravel to the edges of the riverbeds and that helps create point-bars and cut-banks; both important habitats for fish.
The habitat at any given point in a stream is a result of all biotic and abiotic materials found upstream. Those materials are averaged across the stream every time a new tributary flows into the main channel. I once had a fish biologist tell me that, “you never step into the same stream twice.”
As chemicals and minerals move downstream with the spring runoff, spawning fish face the current and attempt to smell the place of their birth. A fish’s ability to sense where its life began, so that it can begin a new reproductive cycle, is an amazing process.
Yellowstone National Park has 11 native fish species and 5 non-native species. The park’s high-mountain geography helps to create the perfect cold water habitat that our fish need. Cold water holds more oxygen than warmer water and can inhibit the spread of some diseases like whirling disease.
Due to drought and thermal run-off, there may be periods in summer where the temperature in the park’s rivers become to warm for trout. If possible, fish move into cooler tributaries during these times.
Yellowstone remains one of the most significant, near-pristine aquatic ecosystems in the United States. With some 2,463 miles of running water and 630 lakes and ponds, all life here relies on a good winter snowpack and it all begins with a single snowflake.