Executive Summary

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This report examines the distribution of healthier remaining populations of eight native trout species in the West. It is the most comprehensive and extensive analysis of its kind.

The report demonstrates that all eight species have experienced severe declines. For all eight, the strongest remaining populations occupy only tiny portions of their former ranges — averaging less than 5%. Three of the eight species have stronger populations in less than 1% of their historic range. Even the strongest remaining populations commonly have experienced local declines and/or occupy partially degraded habitats. Nevertheless, the remaining stronger populations of all eight species were associated with roadless areas. For five of the eight, the majority of their strongholds were in roadless areas.

The analysis clearly indicates that western native trout species are highly imperiled, and complete protection of roadless areas is essential to their persistence. There is a very high risk of continuing loss of stronger populations due to their precarious population status, widespread habitat degradation, and continuing intrusion into roadless areas.

The decline of native trout is caused primarily by habitat damage (much of it associated with roads), and the effects of introduced, non-native fish. Two native trout species are already extinct. Many are listed under the Endangered Species Act.

The Bureau of Land Management (BLM) and Forest Service (USFS) have not protected roadless areas: more than 2.8 million acres of inventoried roadless areas have been lost over the last two decades on USFS lands alone. Millions more acres have been lost on BLM lands. Most remaining roadless areas are not protected from roads, from oil and gas exploration, and other associated degradation.

The report’s results corroborate previous assessments and scientific literature, which have consistently concluded that roadless areas and other high quality habitats are essential components of native trout conservation. Similarly, scientific literature has consistently shown that roads and associated activities are one of the most severe sources of trout habitat damage. This report summarizes this information.

The report is based on computerized Geographic Information Systems (GIS) analysis of trout distributions and roadless areas using data from government and academic sources. The eight native trout species that were analyzed have distributions that cover much of the West and provide a geographically robust indication of the importance of roadless areas for native trout.

In sum, this analysis, the scientific literature, and pertinent government assessments indicates that in the face of the severe declines of these native trout and their dependence on high quality habitat frequently associated with roadless areas, the full protection of all roadless public land, including uninventoried areas greater than 1000 acres, is essential to the restoration and protection of native trout in the West. While such protection is essential, it is not enough. Ensuring even the long term persistence of sensitive trout species will require the widespread protection of depressed and scattered populations, and the recovery and restoration of much habitat. Full recovery of western trout will require proportionately more action yet.