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State of the Lake Superior ecosystem in 2017
Citation:
Mathias, B., T. Hrabik, J. Hoffman, O. Gorman, M. Seider, M. Sierszen, M. Vinson, AND D. Yule. State of the Lake Superior ecosystem in 2017. U.S. Environmental Protection Agency, Washington, DC, 2021.
Impact/Purpose:
The Cooperative Science and Monitoring Initiative provides lake-wide estimates of biomass for both lower and higher trophic level organisms in Lake Superior every five years. These data were used in the development of an EcoPath with EcoSim model to quantify how the Lake Superior ecosystem changed from 2005 to 2016, and to forecast how the ecosystem might change if 2016 harvest levels are sustained until 2055. The model forecasts large changes in the biomass of multiple predator fish that are commercially harvested, but also failed to track current changes in the biomass of a key prey species (cisco), indicating future surveys should provide greater information on this important species.
Description:
The Lake Superior ecosystem, while near-pristine in comparison to the other Laurentian Great Lakes, has seen significant biological changes over the past two decades. Starting in the mid-2000s, pelagic prey fish biomass has been declining in both nearshore and offshore waters (Vinson et al. 2016; Pratt et al. 2016). Declines have been observed in native coregonines, including Cisco, Bloater, and Kiyi, along with Deepwater Sculpin, an important benthic prey in offshore waters (Gorman 2012; Vinson et al. 2016; Pratt et al. 2016). These species comprise a substantial proportion of the diets of native predators like the lean and siscowet forms of Lake Trout, Burbot, and introduced migratory salmonines (Kitchell et al. 2000; Negus et al. 2007; Gamble et al. 2011, 2011b; Isaac et al. 2012). The declines in prey resources are troubling given lean and siscowet Lake Trout populations have remained relatively stable during this time.
URLs/Downloads:
State of the Lake Superior ecosystem in 2017
State of the Lake Superior ecosystem in 2017 (PDF, 5 pp, 402 KB, about PDF)