These data were collected as part of the Southwest Alaska Inventory and Monitoring Network (SWAN) freshwater contaminants protocol. The protocol outlines a framework for monitoring mercury (Hg) concentrations in resident lake fish within SWAN parks. The primary goal of this monitoring is to understand the spatial differences, temporal trends, and health ramifications of Hg contamination in resident lake fish. Monitoring relies on total Hg in fish axial muscle as an indicator of methyl Hg exposure. It targets four high-priority lakes which vary in size, depth, wetland cover, glacial influence, and Hg concentration. These lakes are located in two parks: Lake Clark National Park and Preserve (LACL) and Katmai National Park and Preserve (KATM). The focal species is lake trout (Salvelinus namaycush), a widespread, long lived, top predator in SWAN lakes. However, if other species are sampled as bycatch, they may be retained and analyzed if they represent species-specific data gaps in Hg concentration. Two broad types of data are generated from this protocol. The first type includes observations and measurements that are recorded while sampling and processing fish (e.g., length, weight, gender). The second type includes results of analyses performed by contract laboratories (e.g., age, total Hg). This particular dataset includes those two broad types of data for 49 fish sampled in 2019 and 2020 from 2 lakes in LACL: Lake Clark and Kijik Lake. Of those 49 fish, 40 were lake trout, 6 were burbot (Lota lota), 2 were Arctic grayling (Thymallus arcticus), and 1 was Arctic char (Salvelinus alpinus).

These data were collected as part of the Southwest Alaska Inventory and Monitoring Network (SWAN) freshwater contaminants protocol. The protocol outlines a framework for monitoring mercury (Hg) concentrations in resident lake fish within SWAN parks. The primary goal of this monitoring is to understand the spatial differences, temporal trends, and health ramifications of Hg contamination in resident lake fish. Monitoring relies on total Hg in fish axial muscle as an indicator of methyl Hg exposure. It targets four high-priority lakes which vary in size, depth, wetland cover, glacial influence, and Hg concentration. These lakes are located in two parks: Lake Clark National Park and Preserve (LACL) and Katmai National Park and Preserve (KATM). The focal species is lake trout (Salvelinus namaycush), a widespread, long lived, top predator in SWAN lakes. However, if other species are sampled as bycatch, they may be retained and analyzed if they represent species-specific data gaps in Hg concentration. Two broad types of data are generated from this protocol. The first type includes observations and measurements that are recorded while sampling and processing fish (e.g., length, weight, gender). The second type includes results of analyses performed by contract laboratories (e.g., age, total Hg). This particular dataset includes those two broad types of data for 49 fish sampled in 2019 and 2020 from 2 lakes in LACL: Lake Clark and Kijik Lake. Of those 49 fish, 40 were lake trout, 6 were burbot (Lota lota), 2 were Arctic grayling (Thymallus arcticus), and 1 was Arctic char (Salvelinus alpinus).

These data were collected as part of the Southwest Alaska Inventory and Monitoring Network (SWAN) freshwater contaminants protocol. The protocol outlines a framework for monitoring mercury (Hg) concentrations in resident lake fish within SWAN parks. The primary goal of this monitoring is to understand the spatial differences, temporal trends, and health ramifications of Hg contamination in resident lake fish. Monitoring relies on total Hg in fish axial muscle as an indicator of methyl Hg exposure. It targets four high-priority lakes which vary in size, depth, wetland cover, glacial influence, and Hg concentration. These lakes are in Katmai National Park and Preserve (KATM). The focal species is lake trout (Salvelinus namaycush), a widespread, long lived, top predator in SWAN lakes. However, if other species are sampled as bycatch, they may be retained and analyzed if they represent species-specific data gaps in Hg concentration. Two broad types of data are generated from this protocol. The first type includes observations and measurements that are recorded while sampling and processing fish (e.g., length, weight, sex). The second type includes results of analyses performed by contract laboratories (e.g., age, total Hg). This particular dataset includes those two broad types of data for 40 fish sampled in 2021. Of those fish, all 40 were lake trout.

These data were collected as part of the Southwest Alaska Inventory and Monitoring Network (SWAN) freshwater contaminants protocol. The protocol outlines a framework for monitoring mercury (Hg) concentrations in resident lake fish within SWAN parks. The primary goal of this monitoring is to understand the spatial differences, temporal trends, and health ramifications of Hg contamination in resident lake fish. Monitoring relies on total Hg in fish axial muscle as an indicator of methyl Hg exposure. It targets four high-priority lakes which vary in size, depth, wetland cover, glacial influence, and Hg concentration. These lakes are in Katmai National Park and Preserve (KATM). The focal species is lake trout (Salvelinus namaycush), a widespread, long lived, top predator in SWAN lakes. However, if other species are sampled as bycatch, they may be retained and analyzed if they represent species-specific data gaps in Hg concentration. Two broad types of data are generated from this protocol. The first type includes observations and measurements that are recorded while sampling and processing fish (e.g., length, weight, sex). The second type includes results of analyses performed by contract laboratories (e.g., age, total Hg). This particular dataset includes those two broad types of data for 40 fish sampled in 2021. Of those fish, all 40 were lake trout.

Under the Great Lakes Restoration Initiative, the U.S. Geological Survey Mercury Research Lab (USGS MRL) conducted a multiyear assessment of mercury across the Laurentian Great Lakes. Biannual sampling was conducted across all five lakes onboard the U.S. Environmental Protection Agency (US EPA) research vessel Lake Guardian (in years 2010–2014, 2018) at pelagic sampling locations established by the long-term US EPA Great Lakes monitoring program. In addition to the regularly scheduled biannual sampling, in September 2013 and 2014 Lake Michigan and Lake Erie (respectively) were sampled with increased focus on shallow nearshore locations. Throughout these sampling efforts, sediments, mussels, surface water, and plankton were collected from open-water locations within all five of the Great Lakes. Additionally, surface water from Great Lake tributaries were sampled by the USGS MRL and preceded (2005 or 2006) or overlapped (2010-2015) with the open lake sampling efforts. All surface water samples were analyzed for methylmercury, total mercury, and dissolved organic carbon. Plankton and mussel tissue were analyzed for methylmercury, total mercury, and carbon/nitrogen stable isotopes and concentrations (plankton only). Sediments were analyzed for methylmercury, total mercury, and carbon content.

Under the Great Lakes Restoration Initiative, the U.S. Geological Survey Mercury Research Lab (USGS MRL) conducted a multiyear assessment of mercury across the Laurentian Great Lakes. Biannual sampling was conducted across all five lakes onboard the U.S. Environmental Protection Agency (US EPA) research vessel Lake Guardian (in years 2010–2014, 2018) at pelagic sampling locations established by the long-term US EPA Great Lakes monitoring program. In addition to the regularly scheduled biannual sampling, in September 2013 and 2014 Lake Michigan and Lake Erie (respectively) were sampled with increased focus on shallow nearshore locations. Throughout these sampling efforts, sediments, mussels, surface water, and plankton were collected from open-water locations within all five of the Great Lakes. Additionally, surface water from Great Lake tributaries were sampled by the USGS MRL and preceded (2005 or 2006) or overlapped (2010-2015) with the open lake sampling efforts. All surface water samples were analyzed for methylmercury, total mercury, and dissolved organic carbon. Plankton and mussel tissue were analyzed for methylmercury, total mercury, and carbon/nitrogen stable isotopes and concentrations (plankton only). Sediments were analyzed for methylmercury, total mercury, and carbon content.

Comma-separated values (.csv) file containing data related to mercury in fishes collected from Clear Lake, California.

Comma-separated values (.csv) file containing data related to mercury in fishes collected from Clear Lake, California.

As part of the larger Great Lakes Cooperative Science and Monitoring Initiative (CSMI) , the U.S. Geological Survey Mercury Research Laboratory (MRL) completed a binational assessment partnering with the U.S. Environmental Protection Agency (US EPA), Environmental Climate Change Canada (ECCC), Michigan-DNR (MI-DNR), University of Minnesota-Duluth Natural Resources Research Institute (UM-NRRI), and the National Oceanographic and Atmospheric Association (NOAA), to assess contaminant concentrations within seston, mussels, preyfish, waters, and surface sediments within Lake Huron. All matrices were assessed for mercury and methylmercury concentrations to examine spatial trends of mercury within the lakes. Sediments were also analyzed for total mercury stable isotope composition to approximate sources of mercury contamination to the lake.

As part of the larger Great Lakes Cooperative Science and Monitoring Initiative (CSMI) , the U.S. Geological Survey Mercury Research Laboratory (MRL) completed a binational assessment partnering with the U.S. Environmental Protection Agency (US EPA), Environmental Climate Change Canada (ECCC), Michigan-DNR (MI-DNR), University of Minnesota-Duluth Natural Resources Research Institute (UM-NRRI), and the National Oceanographic and Atmospheric Association (NOAA), to assess contaminant concentrations within seston, mussels, preyfish, waters, and surface sediments within Lake Huron. All matrices were assessed for mercury and methylmercury concentrations to examine spatial trends of mercury within the lakes. Sediments were also analyzed for total mercury stable isotope composition to approximate sources of mercury contamination to the lake.