Ecology and Management of Native Fishes in the Green River

Alpa Wintzer

Native fish populations in the Green River have adapted to the naturally variable environmental conditions of their basin for millions of years. Over the last century, anthropogenic changes in this system have resulted in decreased native fish distributions and abundances. Declines in native fish populations are mostly attributed to two sources. The first is the operation of Flaming Gorge Dam, including the reduction of temperature and seasonal variation in flow, which results in decreased spawning success, poor growth, and habitat that was unfit for the rearing of young. Second, the introduction of non-native fishes negatively impacts natives through competition, predation on young, and the introduction of associated parasites and diseases. The recovery management plan is extensive and includes modifications to the operating procedure of Flaming Gorge Dam to allow flow and temperatures to better mimic natural conditions, non-native species management, stocking of hatchery-reared endangered fishes, research and monitoring, and public outreach. As these imperiled fishes possess life histories that are intimately tied to all facets of the natural system, this type of integrative plan is necessary for success. Its effective planning and implementation, however, can be time- intensive, a luxury that the fishes do not have.