Alturas Lake Research Articles

Anadromy efficacy of native kokanee in Alturas Lake, Idaho

Eaton KR, Tardy KA. 2022. Anadromy efficacy of native kokanee in Alturas Lake, Idaho. Lake Reserv Manage. XX:XX–XX. Partial migration is a complex process that can have profound impacts on ecosystems and populations. Oncorhynchus nerka ecotypes in the Sawtooth Valley include migratory and resident populations, with each exhibiting partial migration. Kokanee can exhibit anadromous behavior and therefore are valuable for O. nerka recovery. In the Sawtooth Valley, Alturas Lake supports a native kokanee population for which the ability to produce outmigrants could influence conservation decisions. In this study, we used contemporary genetic tools to identify the life history origin of Alturas Lake O. nerka outmigrants. Additionally we use population and survival estimates to determine the extent and success of any present kokanee migration. We found that in Alturas Lake, all juvenile outmigrants are progeny of native kokanee. We also found that increased population abundance is related to a higher number of outmigrants. Furthermore, juvenile survival estimates of Alturas kokanee outmigrants were similar to juvenile Redfish Lake sockeye salmon survival estimates. These similar survival estimates and return of anadromous kokanee adults throughout program history indicate that the Alturas Lake kokanee population is successful in exhibiting anadromous behavior. While kokanee are not a focus for O. nerka recovery, this study shows the importance of partial migration in a native kokanee population in preserving the anadromous life history strategy. Our results highlight that in locations with no sockeye salmon population, like Alturas Lake, native kokanee populations are vital to O. nerka recovery and should be monitored and protected accordingly. Supplemental data for this article is available online at https://doi.org/10.1080/10402381.2022.2026541.

Genomic signatures among Oncorhynchus nerka ecotypes to inform conservation and management of endangered Sockeye Salmon.

Conservation of life history variation is an important consideration for many species with trade‐offs in migratory characteristics. Many salmonid species exhibit both resident and migratory strategies that capitalize on benefits in freshwater and marine environments. In this study, we investigated genomic signatures for migratory life history in collections of resident and anadromous Oncorhynchus nerka (Kokanee and Sockeye Salmon, respectively) from two lake systems, using ~2,600 SNPs from restriction‐site‐associated DNA sequencing (RAD‐seq). Differing demographic histories were evident in the two systems where one pair was significantly differentiated (Redfish Lake, FST = 0.091 [95% confidence interval: 0.087 to 0.095]) but the other pair was not (Alturas Lake, FST = −0.007 [−0.008 to −0.006]). Outlier and association analyses identified several candidate markers in each population pair, but there was limited evidence for parallel signatures of genomic variation associated with migration. Despite lack of evidence for consistent markers associated with migratory life history in this species, candidate markers were mapped to functional genes and provide evidence for adaptive genetic variation within each lake system. Life history variation has been maintained in these nearly extirpated populations of O. nerka, and conservation efforts to preserve this diversity are important for long‐term resiliency of this species.

Population Genetic Structure and Life History Variability in Oncorhynchus nerka from the Snake River Basin

AbstractWe used the variation at 64 allozyme loci to examine genetic relationships among 32 samples of sockeye salmon Oncorhynchus nerka and kokanee (resident sockeye salmon) from the Snake River basin and other North American locations. The genetic differentiation among populations was pronounced: Wright's FST was higher (0.244) than has been reported in any other study of Pacific salmon. A detailed examination of the O. nerka from lakes in the Sawtooth Valley of Idaho was undertaken to help guide recovery planning for the endangered Redfish Lake population and to help resolve the relationships between the resident and anadromous forms. In Redfish Lake, adult sockeye salmon that returned in 1991–1993 were genetically distinct from local kokanee but similar to a small group of “residual” sockeye salmon discovered in the lake in 1992. This result is consistent with the hypothesis that the original sockeye salmon population was not extirpated by Sunbeam Dam early in this century. Populations of O. nerka that appear to be native to the Snake River were also found in Alturas Lake, Stanley Lake, and Warm Lake, although the latter two lakes also showed evidence of nonnative gene pools. Kokanee sampled from Pettit Lake are clearly the result of an introduction of late‐spawning kokanee from northern Idaho, and we found evidence of two O. nerka gene pools in Wallowa Lake, both traceable to introductions of nonnative kokanee.

Molluscan Community Composition and Richness in Four High-Elevation Idaho Streams Includes an Exotic Taxon

Abstract: Effective conservation requires that natural resource managers understand the diversity of organisms within a jurisdictional unit. Too frequently, conservation priorities are determined without adequate biological information, leading to inefficient use of very limited resources. We investigated molluscan community composition and richness within the eastern portion of the Sawtooth National Recreation Area (i.e., management unit) in Custer County, Idaho, USA to (1) identify populations of non-native species, if present, (2) acquire baseline information on the distribution, relative abundance, and diversity of molluscs in this high-elevation ecosystem, and (3) provide resource managers with useful information with which to inform conservation priority-setting. We found a rich molluscan community comprised of 19 species from 11 genera and 7 families. We also documented a single population of the non-native species Radix auricularia Linnaeus, 1758 from samples at Alturas Lake. Management of the ver...

Under-ice diel vertical migrations of Oncorhynchus nerka and their zooplankton prey

We used stationary hydroacoustics and measures of environmental conditions (water temperature, dissolved oxygen, light levels, and zooplankton) to determine what factors, foraging or predation risk, influenced diel vertical migrations of Oncorhynchus nerka during winter in three high-mountain lakes. The Sawtooth Valley lakes are deep, oligotrophic, glacial lakes located in central Idaho, U.S.A., and historically contained populations of anadromous O. nerka. In general, low light intensities limited foraging opportunities of O. nerka under ice, especially at night. In Stanley Lake, O. nerka underwent diel vertical migrations to exploit available light to feed. Oncorhynchus nerka occupied shallow water at night, where there was still sufficient light to feed, but were found in deep water during the day. It is unknown whether O. nerka occupied deep depths during the day to feed on high densities of zooplankton or to avoid predators. In Alturas Lake, O. nerka remained in the top 25 m both day and night to feed high densities of zooplankton found near the surface. In Redfish Lake, O. nerka also showed little migration: O. nerka stayed in shallow water both day and night and occupied the same depths with the highest zooplankton densities. The vertical distribution of O. nerka during the winter appears to be determined by available food and light, but the deep daytime distribution found in Stanley Lake is still unexplained.

Hydroacoustic Assessment of Abundance and Diel Distribution of Sockeye Salmon and Kokanee in the Sawtooth Valley Lakes, Idaho

Abstract We used dual-beam hydroacoustics and echo integration techniques, combined with midwater trawling and gillnetting, to assess the abundance and distribution of the endangered Snake River juvenile sockeye salmon and resident kokanee (both Oncorhynchus nerka) in Sawtooth Valley lakes of Idaho during September 1991 and 1992. Abundance of O. nerka varied among the four lakes containing this species (12,500–257,000) and varied between years in Redfish Lake (86,400 in 1994 and 241,000 in 1992) and Alturas Lake (230,000 in 1991 and 257,000 in 1992). In Alturas Lake, where piscivore densities were high and zooplankton densities were low, small acoustic targets (≤18 cm long) were nearly absent from the limnetic zone during daylight, and high densities remained in colder intermediate depths (15–30 m) during crepuscular and nocturnal periods. In Redfish Lake, where predator density was much lower and zooplankton density was higher, targets concentrated in schools at 25–30 m during daylight, dispersed into th...

A List of the Ferns of Idaho

The present enumeration of the ferns of has been compiled mainly from the collections in the herbaria of the following institutions, designated in the list by the appended abbreviations: University of (I), University of Idaho, Southern Branch (ISB), University of Washington (W), Washington State College (WS), Ore. gon State College (OS), and Utah State Agricultural College, Intermountain Herbarium (IH). Additional citations, taken from literature, refer to collections in the Missouri Botanical Garden (M), Gray Herbarium (G), New York Botanical Garden (NY), Academy of Sciences, Philadelphia (Ph), and the United States National Herbarium (US). The extensive collections of C. L. Hitchcock and C. V. Muhlick under the label Flora of Idaho are cited as H. & M. Numbers in. parentheses refer to items cited in the bibliography. The collections are grouped by counties. BOTRYCHIUM LUNARIA (L.) Swartz. CUSTER: Meadowland south of Stanley Lake, H. 4 M. 9675 (IH, W, WS); Bonanza, Macbride Payson (G) (3). BOTRYCHIUM MATRICARIAEFOLIUM A. Br. BOUNDARY: Upper Priest River, Epling 7457 (US) (3). BOTRYCHIUM SILAIFOLIUM var. COULTERI (Underw.) Jepson. BLAINE: Redfish Lake, Henderson 3715 (US) (3). BONNER: Priest Lake, MacDougal 234 (NY) (3). IDAHO: Lolo Trail, Bitterroot Mountains, Piper (WS). LATAH: Moscow, Henderson (US) (3). BOTRYCHIUM SIMPLEX Hitchc. BLAINE: Meadow near head of Alpine Creek, above Alturas Lake, 9000 feet, Cronquist 3720 (IH).