Cooperative Fish and Wildlife Research Units Program: Maine
Education, Research and Technical Assistance for Managing Our Natural Resources

Maine Project

Changing Fish Communities in the Penobscot River After Dam Removal.

January 2019 - December 2022


Participating Agencies


Dam removals re-establish natural flow regimes and increase connectivity, profoundly affecting fish assemblages throughout the watershed. In Maine, the Penobscot River Restoration Project removed the two lowermost dams on the river and improved fish passage at other dams to help recover declining sea-run fishes and increase resilience of entire ecosystems. To quantify spatial and temporal changes associated with river rehabilitation efforts, fish assemblages are being assessed using boat electrofishing surveys (three years each, spring and autumn) prior to dam removal, shortly after removal, and six years post removal (in progress).
Together with NOAA and TNC, we have described distinct fish assemblages present prior to dam, and followed how these communities have changed to a more riverine assemblage. These changes, and their timeline, are important for understanding the management outcomes of dam removal.