Restoration of American Eels to the Susquehanna River Watershed and Implications for Eastern Elliptio Populations

The catadromous American eel occupies a unique niche in estuarine and freshwater habitats along the Atlantic coast. The panmictic population has experienced a range-wide population decline during recent decades. While the Chesapeake Bay watershed supports a large portion of the coastal eel population, a large percentage of the watershed is inaccessible due to mainstem dams on the Susquehanna River. Future hydropower re-licensing of these dams may consider eel passage. We began developing eel collection techniques 2005. In 2008 we began stocking eels upstream of dams to evaluate the reintroduction of eels. Over 590,000 eels have been stocked to date. Laboratory studies conducted by the USGS, Leetown Science Center indicate that eels are the dominant host for the common freshwater mussel, eastern elliptio (Elliptio complanata) in the Susquehanna River. Relative to the adjacent undammed Delaware River where eels are numerous, abundance and recruitment of eastern elliptio in the Susquehanna River is low. Therefore, we believe low abundance and lack of recruitment of eastern elliptio is related to the lack of eels in the Susquehanna River watershed. We are evaluating the effect of eel stocking on recruitment of eastern elliptio and fish species composition in two tributaries to the Susquehanna River.