Lake Michigan map.

The shaded area in the locator map depicts the Great Lakes watershed. White circles are the Fulmar sampling stations pooled across all seasons in 1930–1932. The map was generated by using a geographic information system (GIS) software ArcGIS version 10.4 (http://www.esri.com/software/arcgis/). The GIS map layer for the Fulmar sampling stations was generated in this study. The GIS map layers for Lake Michigan bathymetry, political boundaries, the Great Lakes, and the Great Lakes watershed were obtained from Great Lakes Aquatic Habitat Framework’s [25] public domain spatial database (https://glahf.org/data/).