Last week Bowdoin’s John Lichter, director of the college’s environmental studies program, was featured on local news for his project aimed at helping fish bypass obstacles on their way up Maine rivers. An array of migratory fish species have declined in numbers since the first days of industrialization, blocked from their spawning grounds by a gauntlet of dams.
While it was clear early on that dams caused migratory fish harvests to drop, only recently have researchers been probing the wider ecological and economic impacts. “These fish are feeding the cod and haddock and groundfish species out in the ocean as well,” Lichter said, and their decline has been contributing to the struggles of offshore fisheries.
The Brunswick Hydroelectric Dam, Lichter’s study site on the Androscoggin River, is home to a fish ladder — a sloping series of pools that zigzags from the base of the dam to the top — and a device that creates currents to attract fish to the entrance of the ladder. These measures have helped certain species, like salmon, scale the dam, but have proven particularly ineffective for American Shad. Underwater cameras reveal thousands of shad just downstream of the dam, but far fewer reach the ladder’s entrance—and so far this year only a couple dozen battered individuals have made it all the way up to the top.