Arctic grayling, with their shimmering colors and sail-like fins, once thrived across Montana’s upper Missouri River drainage. Today, only a few populations remain in the lower 48 states. One of their most important refuges is found in the remote Centennial Mountains of Montana. 

Rivers are Life supported a groundbreaking project to learn how these rare fish are adapting to change. Partnering with Louisiana State University’s Fisheries and Movement Ecology Lab, researchers implemented non-invasive underwater video surveys in Red Rock Creek. Over 160 surveys spanned three miles of stream and captured more than 2,000 fish, including 400 arctic grayling. Results showed that a large portion of the grayling population moves from Upper Red Rock Lake into the creek during summer, likely seeking thermal refuge from warm lake waters. 

WHY THIS RESEARCH MATTERS 

Red Rock Creek flows into Upper and Lower Red Rock Lakes, creating the largest wetland complex in the Greater Yellowstone Ecosystem. This place is one of the last strongholds for grayling in the lower 48, but the habitat is under stress. Drought has lowered lake levels, summers are hotter, and winters bring low oxygen. These shifts have taken a toll on grayling numbers and raised urgent questions about how the fish are surviving. This research is beginning to provide answers. 

BUILDING TOOLS FOR THE FUTURE 

The findings reveal more than arctic grayling behavior. They also show how new tools can help conservation. Yellowstone National Park biologists are already exploring ways to adapt this video survey method in their waters. Meanwhile, the LSU team will return each year and expand to nearby tributaries like Elk Springs Creek. These continued surveys will help to develop long term data on arctic grayling abundance in the creek, and the expansion of these surveys will create a better understanding of population dynamics and the role of these streams as thermal refuge for arctic grayling during the summer months.