The role of disease in altering the population structure of Smallmouth Bass in the Susquehanna River

Session: Disease and Mortality in Fishes

Geoffrey Smith, Pennsylvania Fish and Boat Comission, [email protected]
Megan Schall, Penn State Hazleton, [email protected]
Vicki Blazer, U.S. Geological Survey, [email protected]
Heather Walsh, USGS, [email protected]
Tyler Wagner, Pennsylvania State University, [email protected]

Abstract

Several population characteristics are typically accounted for by fisheries managers when managing black bass populations.  These include factors controlled by their environment such as reproduction, recruitment, growth rate, and natural mortality or of anthropogenic origin, like fishing mortality, and are often well understood. The role that disease may play in controlling one or more of these factors is less understood, however.  Beginning in 2005, widespread disease-related mortality affected young-of-year (YOY) Smallmouth Bass at the Susquehanna River and several large tributaries.  Outbreaks varied spatially and temporally; however, the middle and lower Susquehanna and lower Juniata rivers were more severely and consistently impacted.  During some years disease prevalence approached 70%.  Conditions that were favorable for strong year classes coincided with high disease-related morality.  These coupled with occasional years where environmental conditions were not favorable for reproduction and recruitment (i.e., high June-July flow conditions) caused weak year classes or year-class failures for several consecutive years and decreased abundance of adult Smallmouth Bass in a popular and locally economically important recreational fishery. We will review how prolonged disease-related mortality among YOY Smallmouth Bass in the Susquehanna River Basin affected the population and has changed over time.

Twitter handle of presenter
GeoffSmithPFBC