Development and implementation of an adaptive management approach for monitoring non-indigenous fishes in lower Green Bay, Lake Michigan

The Laurentian Great Lakes have had numerous introductions of non-indigenous fishes. Some of these species became invasive, resulting in negative economic and ecological impacts. Given the vulnerability of the Great Lakes to future introductions, monitoring for non-indigenous fishes is necessary to protect the Great Lakes ecosystem. This manuscript describes the adaptive development (2013-2017) and results of an early detection and monitoring (EDM) program for non-indigenous fishes in lower Green Bay and the Fox River, a high-risk location for species introductions in Lake Michigan and a potential vector between the Great Lakes and inland ecosystems. The adaptive management approach to EDM has been a continuous cycle of refining sampling gears and methods to improve monitoring each successive year and determining a new method to assess survey performance (determining the contemporary fish community). To date, no non-indigenous fishes previously unknown to the Great Lakes have been detected. Survey performance (i.e., ability to capture species in the fish communty) of this EDM program has increased since its inception in 2013, and a target of 90% survey performance was achieved or nearly met in 2014-2017. Gears and methods will continue to be adaptively refined; however, the current sampling regime and survey performance should provide effective early detection of new non-indigenous fishes, allowing managers to respond early in the introduction phase, when management actions may be more effective.