Data were created in order to examine mercury concentrations, cycling, and biotic transfer in the Great Lakes and is in response to mercury concentrations in fish that are above consumption advisory levels. This dataset is associated with the following publication: Ogorek, J., R. Lepak, J. Hoffman, J. DeWild, T. Rosera, M. Tate, J. Hurley, and D. Krabbenhoft. Enhanced sensitivity of methylmercury bioaccumulation into seston of the Laurentian Great Lakes. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 55(18): 12714-12723, (2021).