The Acushnet River Restoration Project: Restoring Diadromous Fish Populations to a Superfund Site in Southeastern Massachusetts

The Acushnet River has been the focus of a large-scale effort to restore river herring and American eel populations by improving access into the primary spawning and nursery habitat. Restoration efforts included the construction of a Denil fishway at the New Bedford Reservoir dam in 2002 and the installation of nature-like fishways at two downstream dams in 2007. Monitoring of river herring and juvenile eel (elver) populations was conducted pre- and post-construction using census counting and abundance estimation, respectively. Numbers of adult river herring returning to the reservoir during pre-construction were low and declining numbers of elvers served as a baseline to determine the effectiveness of the new fishways. Results from post-construction monitoring indicated an increasing trend of spawning adult river herring returning to the reservoir with a total count in 2013 representing an increase of 1870% over baseline conditions. Post-construction monitoring also suggests increased elver recruitment into the river, as well as increased numbers of elvers accessing habitat in the upper watershed. Monitoring results suggest that the fish passage improvements to the three dams on the river have improved passage for both elvers and river herring, thereby increasing the probability of restoring these populations to the Acushnet River.