A systematic spatial prioritization method was developed for the US waters of the Great Lakes to identify the highest priority sites for surveillance, based on the likelihood that a watch list species could be introduced. The U.S. waters of the Great Lakes and tributaries were divided into 5,953 standardized units. Of these about 1,800 units have attributes resulting in invasion risk scores greater than zero.
The site prioritization method identifies surveillance priorities for fish, invertebrates, and plants. A comparable site prioritization system is under construction for Canada.