Yellowstone National Park’s supervisory fish biologist, Dr. Todd Koel, has led the Yellowstone Native Fish Conservation Program for the past 25 years. His life’s work has been dedicated to protecting, enhancing, and restoring native fish species in Yellowstone National Park. Dr. Koel’s native fish conservation vision has impacted streams, rivers, and lakes that flow into two oceans, span three states, and provide recreational opportunities to millions of visitors.
Dr. Koel has worked tirelessly to bring Yellowstone Lake’s iconic Yellowstone cutthroat trout back from the brink of extirpation, which was caused by the invasion of predatory, nonnative lake trout. Thanks to Dr. Koel’s leadership, the expansive Yellowstone Lake restoration program has reduced the biomass of adult lake trout by a staggering 94 percent. Over the past 30 years more than 4.75 million lake trout have been gillnetted, with 264,613 lake trout removed in 2024 alone.
Dr. Koel has also led the testing of novel suppression methods to control lake trout, including the use of helicopters to distribute plant-based pellets that smother lake trout spawning areas, inducing embryo mortality. Due to Dr. Koel’s leadership, Yellowstone cutthroats are returning to their spawning streams, repopulating their ecosystem, and are once again thriving in spite of the remaining lake trout. The accomplishment of greatly diminishing one fish species in an ecosystem while preserving another cannot be overstated.
Dr. Koel has also been at the forefront of native fish stream and lake restoration projects. He has advocated for the implementation of rotenone and translocation-restoration projects in the greater Yellowstone ecosystem to eliminate nonnative fish and restore native fish to their historic habitats, collaborating with numerous state, federal, private, and nongovernmental organizations along the way. Because of his monumental efforts and foresight, Yellowstone cutthroat trout, westslope cutthroat trout, and Arctic grayling have been restored to 88 stream miles and 281 lake acres in Yellowstone where they had previously been extirpated. In 2024, natural reproduction of native westslope cutthroat trout and Arctic grayling was documented in the upper Gibbon River watershed, a testament to the project’s success.
Dr. Koel is a driving force in research-based management and for furthering our scientific knowledge in the greater Yellowstone ecosystem. As of January 2025, he has authored or coauthored 117 scientific publications. He has served as a review committee member for more than 30 graduate students, and has mentored a small army of seasonal employees, biologists, and researchers on numerous projects and studies.
He has also championed the protection of Yellowstone’s waters against invasive species. Dr. Koel’s research has led to the implementation of commonsense regulations with strong scientific backing to protect Yellowstone National Park from aquatic invasives. Much of this work would not have been possible without Dr. Koel’s “let’s make this happen” approach and his ability to communicate the importance of such work to the public.
Dr. Koel has built an unparalleled legacy for native fish conservation that will give future generations of Yellowstone National Park visitors the opportunity to experience native fish thriving in the watersheds where they belong. Because of his work, Yellowstone National Park’s entire ecosystem is wilder and more pristine, a shining example to the world of what a national park can be.
