Interviews, footage, and editing by Kate Dawson.
Underwater footage courtesy of Stephen Coghlan.
Maine's rivers were once linked to the ocean by spawning migrations of diadromous fishes. These fish brought nutrients and energy from the marine realm hundreds of miles into upland, freshwater food webs. Dams, constructed to power mills and later generate electricity, blocked these fish migrations, resulting in decreased biodiversity and productivity. The Penobscot River Restoration Project will open potentially thousands of kilometers of historic fish habitat, with ecosystem-wide effects anticipated. However, scientists lack empirical data about how systems respond to dam removal at the species, community, and ecosystem levels.
Sedgeunkedunk Stream, a tributary of the lower Penobscot River estuary, is the subject of a restoration effort to reconnect the stream and its associated lakes to the sea. One dam has been removed and another bypassed with a rock-ramp fishway and monitoring programs are in place for fish and macroinvertebrates. Coghlan's project focuses on the sea lamprey, a native, anadromous ("sea-run") fish whose nest-building activity creates habitat for another anadromous fish, the endangered Atlantic salmon.