Yellowstone Lake Features & History

Lake Characteristics

Yellowstone Lake is a large, oligo-mesotrophic lake (Theriot et al. 1997) located centrally in Yellowstone National Park, Wyoming. The lake is the largest lake above 2,000 m in elevation at 2,357 meters above sea level (masl) with a surface area of 34,020 ha, a mean depth of 48m, and a maximum depth of 133 m (Kaplinski 1991). Formed by a series of volcanic eruptions and magma chamber collapses (Morgan et al. 2003), the lake has two major basins with hydrothermal activity concentrated in the West Thumb Basin (Kaplinski 1991). The lake is typically ice covered from mid-December until late May or early June. Water temperatures fluctuate between 9°C and 18°C in the summer (Ruzycki et al. 2003) and a thermocline develops during stratification from July through August at about 15 m (Koel et al. 2007).

The lake has a unique assemblage of organisms. The phytoplankton assemblage is dominated by diatoms throughout the year (Benson 1961; Tronstad et al. 2010). The primary zooplankton community includes the rotifer Conochilus unicornis, Copepoda Diaptomus spp., Cyclops spp. and Cladocera Daphnia spp. Macroinvertebrates including amphipods Hyallela spp. and Gammarus spp. make up the non-insect assemblage in the lake while insects such as tricopterans, dipterans, and ephemeropterans complete the benthic taxa. The fish assemblange consists of both native and nonnative species. The native fishes include Yellowstone Cutthroat Trout and Longnose Dace (Rhinichthys cataractae). Lake Trout, Longnose Sucker (Catastomus catostomus), Redside Shiner (Richardsonius balteatus), and Lake Chub (Couesius plumbeus) were introduced into Yellowstone Lake (Gresswell and Varley 1988).

Lake History

Invasive trout, along with hybridization (Kruse et al. 2000), act in concert and contribute to the decline, and often extirpation, of Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri) across their native range. The effect of Lake Trout (Salvelinus namaycush) on Yellowstone Cutthroat Trout populations through predation and competition for limited resources in lake ecosystems (Syslo 2010) is of particular concern for conservation of Yellowstone Cutthroat Trout. Yellowstone National Park initiated an ongoing Lake Trout suppression program in Yellowstone Lake in 1995. To increase the success of meeting suppression program goals, the program initiated novel embryo suppression techniques in 2016, which includes using whole and ground Lake Trout carcass material on spawning substrate to cause hypoxic conditions unsuitable for developing Lake Trout embryos (Thomas 2017). Addition of Lake Trout carcass material increased Lake Trout embryo mortality in controlled experiments to near 100% (Thomas 2017) and could be applicable to suppression of Lake Trout embryos lake-wide.