Growth of Re-Introduced American Eels in a Susquehanna River Tributary

American Eels have been precluded from a major portion of the Susquehanna River since the construction of Conowingo Dam in 1928.  In 2008, USFWS began collecting and transporting elvers above the four mainstem dams on the Susquehanna River.  As part of a mitigation project, elvers were specifically stocked into two tributaries of the Susquehanna, Buffalo Creek and Pine Creek.  In order to determine how well stocked eels were growing, fish greater than 200 mm were PIT-tagged beginning in fall of 2012 at two sites within Buffalo Creek.  Over 500 eels have been tagged, and 23 have been recaptured.  On average, recaptured eels have grown 58.1 mm per year (SD= 26.1), with growth ranging from 14-114 mm per year.  These growth rates are higher than many published reports for American Eels in freshwater streams, and are higher than observed growth rates of eels below Conowingo Dam, where growth averages 42.7 mm per year.  Sexual differentiation has occurred in some translocated eels.  In 2014, 10% of eels captured at a site in Buffalo Creek were identified as silver males and several large females were caught as well.  Moving eels above major blockages may lower local population density and increase growth rates.