This article examined the characteristics of the population of Humboldt cutthroat trout (Salmo clarki spp.) in Chimmney Creek, Nevada, during four years of abnormal spring flows. Fish populations fluctuated over this period; with the most depressed levels occurring during the drought year of 1981 and the record runoff of 1984. This difference can likely be attributed to relatively weak young of the year (YOY) classes, particularly in 1981 when no YOY individuals were encountered. In 1982, the YOY class exhibited its greatest strength, but the absolute number of adults was at its lowest point of the study. There was a split YOY class observed in 1983 with two distinct subpopulations (length-classes) of YOY individuals collected in 1983, that were separated by an average of 20 mm. This suggests the occurrence of at least two spawning periods as evidenced by the hydrograph from 1983. Although the mechanism responsible for promoting two subpopulations of spawners is not known, the adaptive advantage is clear: sufficient genetic diversity is present to ensure successful reproduction during the most irregular of weather patterns. Many interior watersheds are degraded and it seems clear that tolerant species such as the Humboldt cutthroat could provide a valuable resource for stocking into habitats generally deemed unsuitable for trout.
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