Salmonfly Study

Salmonfly Study - Summer 2024

Dr. Lindsey Albertson and graduate student Zach Maguire at Montana State University have an ongoing program studying aquatic invertebrates---a scientific term for a fly fisher’s favorite “bugs” on the river.  The project has two parts -- first, accumulating and evaluating years of water temperature data on the Madison and second, assessing the impact of tributary flow, temperature, sediment and other variables on invertebrate populations below the tributary’s confluence with the mainstem river. The result of this project will help scientists better understand river and tributary conditions that impact invertebrate populations and diversity.

The Madison River Foundation is supporting this effort with funding for an extra technician to help evaluate and collect data in 2024. MRF staff member Casey Cooper will be assisting Dr. Albertson and Felicia King, an AP Biology teacher at Gallatin Valley High School who has collected samples in previous years. Primary tasks will be to record the timing and amount of salmonflies emerging during the hatch. Additionally, Felicia has some preliminary data to indicate that salmonflies prefer to emerge on vegetation (or other structures) that have some height to them, rather than sand or cobble. This summer, Casey and Felicia will work on an experiment where they put out vegetation “mimics” of different heights (e.g., 10 cm, 20 cm, 40 cm) at two sites on the Madison River (Hebgen Dam and Varney Bridge) and count shucks on them to test the hypothesis that salmonflies prefer to crawl upwards before casting aside their shuck (exoskeleton) and flying away, and that their emergence success (dead vs. alive inside the shuck) is higher when the vegetation is taller. If the data support this hypothesis, then the findings could point toward riparian plantings as a management tool to increase salmonfly emergence success, which then could potentially indicate that more eggs are produced for the next generation.