U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 108, May 2010


US government work


The Gila National Forest in southwestern New Mexico harbors two imperiled aquatic species in its mid-to-high elevation streams, the Gila chub and the Gila trout. Modern and historical land use pressures, and the introduction of non-native fishes, have reduced the range of the Gila trout to a handful of headwater streams. The remaining populations are highly fragmented. The Gila National Forest was an early pioneer in the use of naturally ignited wildfire to achieve resource benefi ts. Fish populations can be harmed by fire in some cases, however, even when they have evolved with fire. This occurs when populations dwindle and fi sh habitat connectivity changes through introduction of non-native fish and human impacts downstream, which sometimes make it difficult for fish to migrate to a more favorable location. A retrospective study using satellite sensor and weather information has documented the effects of forest composition, elevation and slope, snow pack, and seasonal and annual variability in precipitation on burn severity in the Gila. Information on past burn severity may help resource managers plan for actions before and during fire seasons to ensure the long-term survival of the Gila trout and Gila chub. In addition, predicting the likelihood and location of severe fire and potential debris and ash flows can help managers decide which streams are best suited to support fish populations for the long term. The ultimate aim is to bolster populations of native trout and promote connectivity of habitat where the fish stand a good chance of thriving. The fate of the endangered chub is even more precarious.