Abstract
Currently one small, native population of the culturally and ecologically important Lahontan cutthroat trout (Oncorhynchus clarkii henshawi, LCT, Federally listed) remains in the Truckee River watershed of northwestern Nevada and northeastern California. The majority of populations in this watershed were extirpated in the 1940s due to invasive species, overharvest, anthropogenic water consumption and changing precipitation regimes. In 1977, a population of cutthroat trout discovered in the Pilot Peak Mountains in the Bonneville basin of Utah, was putatively identified as the extirpated LCT lacustrine lineage native to Pyramid Lake in the Truckee River basin based on morphological and meristic characters. Our phylogenetic and Bayesian genotype clustering analyses of museum specimens collected from the large lakes (1872–1913) and contemporary samples collected from populations throughout the extant range provide evidence in support of a genetically distinct Truckee River basin origin for this population. Analysis of museum samples alone identified three distinct genotype clusters and historical connectivity among water bodies within the Truckee River basin. Baseline data from museum collections indicate that the extant Pilot Peak strain represents a remnant of the extirpated lacustrine lineage. Given the limitations on high-quality data when working with a sparse number of preserved museum samples, we acknowledge that, in the end, this may be a more complicated story. However, the paucity of remnant populations in the Truckee River watershed, in combination with data on the distribution of morphological, meristic and genetic data for Lahontan cutthroat trout, suggests that recovery strategies, particularly in the large lacustrine habitats should consider this lineage as an important part of the genetic legacy of this species.
Highlights
The integrity of freshwater ecosystems is threatened by invasive species, human water consumption and changing precipitation regimes
The inland cutthroat trout subspecies (Oncorhynchus clarkii spp.) are cold water fishes that were heavily impacted by European expansion into western North America, with many listed as threatened or endangered under the United States Endangered Species Act (ESA)
We report on genetic results that support the rediscovery of a lacustrine form, long thought to be extinct, of Lahontan cutthroat trout (O. clarkii henshawi, LCT), an ESA-listed (USFWS Federal Register vol 40, p. 29 864) native to the Lahontan hydrographic basin of northern Nevada, northeastern California and southeastern Oregon, in waters outside the native range
Summary
The integrity of freshwater ecosystems is threatened by invasive species, human water consumption and changing precipitation regimes. The inland cutthroat trout subspecies (Oncorhynchus clarkii spp.) are cold water fishes that were heavily impacted by European expansion into western North America, with many listed as threatened or endangered under the United States Endangered Species Act (ESA). These fishes were once found throughout the intermontane western USA in multiple-order stream and lake habitats. We report on genetic results that support the rediscovery of a lacustrine form, long thought to be extinct, of Lahontan cutthroat trout (O. clarkii henshawi, LCT), an ESA-listed (USFWS Federal Register vol 40, p. 29 864) native to the Lahontan hydrographic basin of northern Nevada, northeastern California and southeastern Oregon, in waters outside the native range (figure 1)
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