New research maps future of freshwater fish habitat conservation

ANCHORAGE, AK (March 5, 2026) - Freshwater fish around the globe are under increasing pressure from habitat loss, climate change and human development. But now, high-resolution methods of mapping waterways can stem those trends, starting by identifying the places fish need most.

Published in the Nature journal Scientific Reports, a new study conducted across Alaska demonstrates how higher resolution digital elevation data are being used to reveal previously unmapped rivers, streams and habitat connectivity that are essential for salmonid populations, like salmon and whitefish. 

The new research, led by Dr. Lee Benda at Terrainworks and others, led to development of “virtual watersheds” to support resource management, stream restoration and conservation.

The research helps identify the places fish need most at a time when one-quarter of the world’s freshwater fauna are threatened with extinction

“How can you protect streams and rivers, and salmon habitats, if they are not on a map?” said lead author Dr. Benda. “Our study describes an evolution of riverscape science where high resolution virtual watersheds are now replacing older, incomplete cartographic products developed decades ago.”

Using radar and laser digital elevation products, virtual watersheds comprehensively identify stream networks and connect them to other important watershed elements, including lakes, riparian areas, wetlands and the terrestrial system. These maps reveal extensive potential fish habitats across southeastern rainforests to the Arctic coastal plain. Previously unidentified headwater tributaries and valley bottom channels represent tens of thousands of kilometers of new streams and their habitats.

Jason Leppi, Ph.D., lead fisheries biologist for The Wilderness Society, who was a co-author on the study, said “the newly developed hydrography and virtual watersheds provide critical information to accurately quantify available fish habitat, inform management decisions, and identify freshwater conservation opportunities in Alaska.”

The problem the research team confronted in Alaska—poor quality and incomplete mapping of streams and aquatic habitats—is a problem of global proportions. Across much of the world, accurate maps and information on stream networks remain lacking. Even in the contiguous U.S., where streams are derived using more modern methods, official hydrography maps often do not accurately represent headwater streams and have limited analytical capabilities necessary to identify fish habitats. Thus, the new virtual watershed science and technology present an opportunity to improve freshwater conservation and restoration worldwide. It couldn’t be timelier: A recent paper in the journal Nature found that one-quarter of the world’s freshwater fauna are threatened with extinction. 

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