Where the fish end: Predicting the upper reaches of fish habitat

Abstract

Establishing riparian zones to protect fish has been a standard forest management practice in western Oregon and Washington for decades. But to effectively place these zones, one needs to know where fish are living.

Brooke Penaluna, a research fisheries biologist with the U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, has led the development of a new model that predicts the presence of fish more accurately than previous models or other methods, which relied heavily on electrofishing— a labor-intensive method of manually surveying streams.

Her new model, called UPRLIMET, uses light detection and ranging (LiDAR) mapping and computer algorithms to provide the most accurate picture to date of where fish are likely to live in a watershed. In western Oregon, the model predicted coastal cutthroat trout were farther upstream than had been previously estimated.

While she was working on UPRLIMET, Penaluna built on her previous research of environmental DNA (eDNA)—traces of genetic material left by hundreds of different species in rivers and streams—that confirmed UPRLIMET’s prediction of extended occurrence.

Together, UPRLIMET and eDNA analyses are highly accurate and noninvasive methods for showing where fish live. They can be used as conservation tools by both public and private forest managers.

Citation

Kirkland, John; Penaluna, Brooke. 2025. Where the fish end: Predicting the upper reaches of fish habitat. Science Findings 274. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.