Strategic Planning and Resource Assessment

Forest Service 2003 Success Stories

Success Stories: The Role of Introduced Trout in High Elevation Lake Ecosystems in the Sierra Nevada

The stocking of streams and lakes of fish occurs throughout the world to increase sport fishing opportunities, yet little consideration has been given to the potential consequences of these introductions on native species. In California , there was growing concern that exotic, or introduced , trout were playing a role in the decline of the mountain yellow-legged frog - once common in this area - where historically no native fish existed in the High Sierra. A study to determine the impact of introduced trout on the native biota of high elevation lakes in the Sierra Nevada was initiated in 1995, sampling over 2,000 lakes in the John Muir Wilderness and Kings Canyon National Park. This is a collaborative research effort among Pacific Southwest (PSW) Forest Service, University of California Santa Barbara, and Michigan State University.

This research study has demonstrated a link between fish stocking and observed decline of the mountain yellow-legged frog, once the most common vertebrate animal in the Sierra Nevada . The work also provided information on the effect of non-native trout on the entire high-elevation aquatic ecosystem including invertebrates, garter snakes, and other amphibians, and the potential for recovery. The resulting research and 11 publications have contributed to the scientific literature in conservation, fundamental ecology of aquatic habitats, applied ecology and management, and the natural history of the mountain yellow-legged frog.

Now the California Department of Fish and Game and the Sequoia-Kings Canyon National Park are using our research to implement new management strategies.

The most valuable aspect of the research findings is that we can now predict that, with some simple management changes (i.e., reduced fish stocking), the impacts of exotic fish introductions can be reversed, and that these important high elevation ecosystems can be restored. It may be possible to manage for trout and native species and reduce conflicts between the competing user groups.

Figure 1

Map showing the John Muir Wilderness and Kings Canyon National Park Study Areas.

USDA Forest Service - Strategic Planning and Resource Assessment
Last Modified: Tuesday, 18 May 2004 at 11:33:57 EDT