The Gulf of Maine Research Institute and Presumpscot Regional Land Trust will lead a walk during the annual alewife migration season at Mill Brook Preserve in Westbrook. The walk will be a two-mile round-trip on uneven, hilly terrain. GMRI Research Scientists, Zach, and Aaron, will guide participants through the process of observing and collecting data on these fascinating fish while Brenna, from the Presumpscot Regional Land Trust, will talk about the importance of preserving critical habitat.