Yellowstone's Trout War: Millions Removed, Native Fish Return

Yellowstone Lake is undergoing a significant ecological recovery as park rangers and researchers continue a large-scale effort to suppress invasive lake trout. Since their introduction in the 1980s, these non-native fish have severely impacted the native Yellowstone cutthroat trout, a vital food source for wildlife. Annual gillnetting operations have intensified, exceeding benchmarks and leading to a substantial decrease in lake trout biomass.

By 2019, lake trout biomass had fallen significantly from its 2012 peak, primarily due to a reduction in adult fish. This suppression has allowed native cutthroat trout to begin returning to spawning streams, with wildlife like grizzly bears and bald eagles showing renewed presence. Innovative methods, including spreading organic pellets to reduce egg survival, are being explored alongside continued netting.

Despite millions of lake trout removed, reaching over 4.9 million by 2024, the native cutthroat trout population has not yet fully met management targets. However, surviving native trout are showing signs of improved health, with larger average sizes and doubled individual weights, suggesting reduced competition for resources. The program relies on ongoing funding and monitoring to ensure the long-term health of Yellowstone's native fishery and ecosystem.