Recent Changes in Population Characteristics of Smallmouth Bass at the Middle and Lower Susquehanna River and Lower Juniata River

Elaine Langone Center, Forum

Wide-spread disease related mortality of young-of-year Smallmouth Bass beginning in 2005 affected recruitment and resulted in a substantial decline in abundance of adult Smallmouth Bass in popular and locally important recreational fisheries in the middle and lower Susquehanna River and lower Juniata River. In recent years, the prevalence of disease has decreased; resulting in increased recruitment and changes in population characteristics. Catch rates of adult Smallmouth Bass (age-1 and older) determined during nighttime boat electrofishing surveys conducted at the middle Susquehanna River, lower Susquehanna River, and lower Juniata River have increased recently and have been at or above the long-term median values during 2014 and 2015 at all three reaches. Additionally, electrofishing catch rates of Smallmouth Bass 375 mm and longer in total length have varied but remained similar to or increased at all three reaches. The age and size distribution of Smallmouth Bass has also changed in recent years at the middle Susquehanna River as the catch rate of smaller and younger fish has increased during the 2013 -2015 surveys. This represents a shift towards a population age and size structure more similar to the pre-2005 period. We will discuss recent data analysis that was conducted, in part, though funding provided by the RK Mellon Freshwater Research Initiative at Susquehanna University.