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Study Suggests Dam Removal Can Restore Native New England Fish Species

Great Lakes Environmental Research Laboratory - NOAA

Researchers are claiming that it’s possible to save important native New England fish species if certain upgrades and removal of existing infrastructure can be made. WAMC’s Lucas Willard has more…

Ecologists from UMass Amherst and Stony Brook University in New York are saying that although the survival of some species of river herring in New England is threatened, work can be done to restore the small fish to healthy populations.

The theory comes from a study funded by a Mia J. Tegner Memorial Research Grant and the National Oceanic and Atmospheric Administration. Adrian Jordaan, who worked on the study, show that damming up waterways that lead to the ocean can significantly impact populations of native alewife and blueback herring. Jordaan says the fish, which migrate upriver from the ocean, play a critical role in the ecosystems of New England’s rivers by bringing a source of food and nutrients.  

The study itself focused on nine Maine rivers, and analyzed dam records to find where fish populations were being prevented from accessing their native habitat by dams built between 1600 and 1900. Researchers estimated that by 1850, about 1.4 billion fish per year were missing from the “system”. Jordaan says that although the study focused in Maine, the results highlight a regional issue.

Carolyn Hall, now an independent researcher who authored the study, said that successful restoration of the species can occur in places where the dams are removed. She said that by reintroducing the herring species to their native spawning grounds, predatory species such as eagles and ospreys may also return to the area. Fish that eat the herring such as cod and striped bass may also increase in numbers, which can be important for fishing economies. Hall added that by understanding the historic numbers of the fish, agencies can further understand river herring species which can help set conservation goals.

In the past legislative session, Massachusetts lawmakers did not successfully pass a bill that would allow for the removal and restoration of the hundreds of old dams that exist in the state. The Nature Conservancy supported the bill, saying the removal of old dams in will significantly benefit local ecosystems.

Lucas Willard is a news reporter and host at WAMC Northeast Public Radio, which he joined in 2011. He produces and hosts The Best of Our Knowledge and WAMC Listening Party.