Clean Air Regulatory Agenda Freshwater Inventory and Surveillance of Mercury (CARA FISHg)

Environmental quality data from water, fish and sediments in 20 lakes across Canada. Measurements include mercury, methylmercury, physical-chemical parameters such as pH and alkalinity, stable isotopes, fish biological data, nutrients, ions, and metals. The data collection includes sites with a period of record ranging from one year to eight years, starting in 2008. Fish analysed at each site include at least one top predator species and one prey species.

The national CARA FISHg network was a sub-project of the Ecological Risk Mapping Project under the Clean Air Regulatory Agenda’s Mercury Science Program. Its goal was to systematically monitor levels of mercury in freshwater fish and aquatic ecosystems to identify changes in mercury concentrations over time. In most cases, lakes were sampled once per year in the fall. Exposure lakes were sampled near Canadian point source atmospheric mercury emissions. Background lakes, far from known local emissions sources, were chosen to assess the influence of global versus Canadian atmospheric mercury emissions on fish mercury levels. Where possible, exposure and background lakes were chosen that had no watershed connectivity to other lakes or to large river systems, no stocked fish, and no runoff/land-based mercury inputs.