Identifying species that pose a threat to the Great Lakes is an important strategy within an early detection program and can help inform what to look for and where to look. 

Development of a watch list of priority, high-risk species should be based on the probability of introduction, establishment, and impact in the Great Lakes. Only those species that are present in an active pathway of introduction (such as the aquarium trade or recreational boating), can establish self-sustaining populations, and are likely to have a high or moderate ecological and/or socio-economic impact would be considered a high-risk species.

A watch list can also help inform which habitats should be monitored, and what methods and approaches (including frequency of monitoring) should be deployed to increase the likelihood that high-risk species will be identified soon after introduction, as well as increase the potential for a successful management response when high-risk species are discovered.