Academic literature on the topic 'Henry's Lake (Idaho)'

Ghost-dune hollows on the eastern Snake River Plain (ESRP), Idaho, USA, are topographically inverted, crescent-shaped depressions that record the partial encasement of sand dunes by ca. 61 ka basalt lava flows. Deflation of these “ghost” sand dunes produced approximately two dozen, 5–10-m-deep ghost-dune hollows now incompletely filled with pedogenically altered eolian and colluvial sediment. Optically stimulated luminescence (OSL) and 40Ar/39Ar ages constrain a ghost-dune hollow model that illuminates the late Pleistocene to Holocene environmental and climate history of the ESRP. Detrital zircon analyses indicate sand-dune supply routes changed following the burial of Pleistocene Henrys Fork (tributary of the Snake River) alluvium by ca. 70 ka basalt flows. Removal of Henrys Fork alluvium from the eolian supply system made Lake Terreton sediment the primary source for later ESRP sand dunes. Such sediment supply changes highlight the potential impacts of effusive volcanism on sand-dune histories and landscapes. Our results support stratigraphic and sedimentary modeling of comparable ghost-dune “pit” deposits older than ca. 2 Ga on Mars that may have served as refugia for early life on that planet. Analogous ancient ghost-dune hollow deposits on Earth may also have served as early life refugia.

The Centennial Mountains are an east-west trending mountain range in southwest Montana. The Centennial Mountains are bound on the south by the Eastern Snake River Plane, the north-trending Madison Range and fault on the east and the Centennial Valley on the north. The Centennial normal fault offsets the Centennial Mountains on the north down-dropping the Centennial Valley. Approximately 3000 meters of offset along the Centennial normal fault creates the Centennial Mountains. The present Centennial Mountains are subdivided into two stratigraphically different blocks by the Odell Creek normal fault. The eastern Centennial Mountains are interpreted as the upthrown block of the Odell Creek normal fault exposing Precambrian and Paleozoic rock along the northern face of the range. The western Centennial Mountains are interpreted as the downthrown block of the Odell Creek normal fault exposing Cretaceous and younger rocks. Both eastern and western segments of the Centennial Mountains are then offset along the range bounding Centennial normal fault. Offset along the Centennial normal fault started approximately 2.1 Ma as evidenced by the displacement of the 2.1 Ma Huckleberry Ridge tuff. It is believed that prior to the emplacement of the 2.1 Ma Huckleberry Ridge tuff, the Centennial Mountains had minimum to no surface relief. The majority of offset along the Centennial normal fault has occurred with in the late Pleistocene with estimated slip rates of 0.65-0.82 mm/yr. The late Pleistocene surface offsets along the Centennial Mountains have an average of 9.1-9.6 meters with similar offset seen along the eastern and western segments.

<em>Abstract</em>.—The Idaho Department of Fish and Game has stocked fingerling Yellowstone cutthroat trout <em>Oncorhynchus clarkii bouvieri</em>, hybrid trout (rainbow trout <em>O. mykiss</em> × Yellowstone cutthroat trout), and brook trout <em>Salvelinus fontinalis </em>(hereafter referred to collectively as trout) in Henrys Lake since the early 1900s to supplement natural recruitment and increase angler catch rates. Annual stocking rates have varied from 317 to 1,027 fingerling (approximately 75 mm) trout per hectare from 1971 to present. Stocking densities can influence angler catch rates but are limited by production constraints and costs associated with raising and transporting fish. By refining fingerling trout stocking densities, managers can optimize the fishery and minimize hatchery expenditures. To fully understand the effects of stocking density on angler catch rates in a lake with natural reproduction, we estimated the contribution of hatchery fish to the fishery by analyzing 6 years of marked fingerling stockings and found that natural recruitment added little to the adult population. We then explored the relationships among stocking densities, angler catch rates, and size of fish harvested by anglers to determine the optimal stocking density needed to achieve our management objectives of catch rates 0.7 fish per hour and 10% of harvested Yellowstone cutthroat trout exceeding 500 mm. We found increased catch rates following years when stocking densities were high. However, mean size of Yellowstone cutthroat trout harvested decreased following years of higher stocking densities. We estimate that approximately 737 fingerling trout per hectare are needed annually to achieve angler catch rates of 0.7 fish per hour. At this stocking density, we estimated that approximately 3% of harvested Yellowstone cutthroat trout would exceed 500 mm. This fell below our management objective of 10% of harvested Yellowstone cutthroat trout exceeding 500 mm and suggested that our current catch rate objective and size objective may be incompatible. This information should be combined with angler opinion data to formulate attainable goals for the fishery.