Past and Present Genetic Structure of Striped Bass Populations in the Carolinas

In order to properly manage a species over a large geographic area, it is necessary to understand the genetic connectivity both among and within river systems in order to identify appropriate manage­ment units.  Determining changes in this connectivity is also important in understanding how stocking might have changed these genetic relationships.  Previous studies on striped bass from 1992-1994 found differentiation between the ACE Basin, Santee-Cooper System, and Pee Dee System but no differentiation within the Santee-Cooper using three RFLP markers.  Using twelve microsatellites to give a higher resolution, we investigated the striped bass populations of four Carolina watersheds in order to determine if they are genetically distinct; if the Santee-Cooper currently contains distinct within-watershed populations; and if these relationships have changed over time with contemporary (2006-2011) and historic (1991-1994) collections.  Our results show striped bass populations within the Santee-Cooper continue to have a large amount of gene flow.  Populations were determined to be distinct across watersheds both in contemporary and historic times; however there has been a decrease in genetic differentiation between the ACE Basin and Santee-Cooper system.  Using admixture analysis, there is also indication of current migration between the Roanoke system and Santee-Cooper system although it is unclear if this is a result of downstream or coastal movement.  The project results have increased our understanding of striped bass population dynamics across the Carolinas, allowing for improved management and restoration efforts for striped bass.