Salmonfly Study

A Collaboration with Montana State University

The Salmonfly (Pteronarcys californica) is a large-bodied aquatic insect that lives in rivers for 3 to 5 years before emerging onto land as an adult. The salmonfly hatch is iconic, drawing anglers from around the world, and represents a major connection between water and land. During the hatch, salmonflies are a critical food source for trout, birds, and many other predators. Salmonflies are threatened by human activities however; threats to salmonflies and other stoneflies include warming water temperature, increasing fine sediment, and changes to suitable flows and food supply. We study factors that influence salmonfly populations and their emergence patterns, with a focus on the Madison and Gallatin Rivers in southwestern Montana. In collaboration with researchers across Montana and beyond, we use historical records, field studies, and lab experiments to link knowledge of salmonfly ecology with potential conservation strategies to help maintain populations of this incredible insect into the future.

Dr. Lindsey Albertson at Montana State University has 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 main stem 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 and volunteers to help collect and evaluate data. Primary tasks will be to record the timing and amount of salmonflies emerging during the hatch. The findings could point toward further conservation efforts such as riparian plantings and wooden post installations as management tools to increase salmonfly emergence success, which then could potentially indicate that more eggs are produced for the next generation.