Habitat Fragmentation and Extinction Risk of Lahontan Cutthroat Trout

We used survey data collected by the Nevada Division of Wildlife to analyze presence or absence of Lahontan cutthroat trout Oncorhynchus clarki henshawi in relation to habitat fragmentation (isolation), habitat size and shape, presence or absence of nonnative salmonids, elevation, latitude, longitude, and precipitation regime for 119 stream basins in the eastern Lahontan basin. Multiple logistic regression analysis revealed stream basin isolation to be the only significant correlate of Lahontan cutthroat trout occurrence. Eighty-nine percent of stream basins connected to another basin containing Lahontan cutthroat trout also supported Lahontan cutthroat trout, while only 3290 of isolated stream basins supported Lahontan cutthroat trout. This analysis highlights the potentially negative effect of habitat fragmentation on population persistence for this threatened species.