Conservation Impacts of Hybridization Between Native Bartram's Bass Micropterus Sp. Cf. M. Coosae and Two Introduced Species in the Savannah Basin

Bartram’s bass Micropterus sp. cf. M. coosae is endemic to the Savannah basin of South Carolina and Georgia.  Hybridization between this native species and introduced Alabama bass M. henshalli is widespread in the upper portions of the drainage.  Recent studies have documented a precipitous decline in genetically pure Bartram’s bass in Savannah River reservoirs, and a corresponding increase in fish of hybrid origin.  We surveyed tributary populations associated with the reservoirs and with the Savannah main stem in 2004 and 2010.  Results indicate an increased occurrence of hybrids in Bartram’s bass native stream habitats over time, and also document the new occurrence of a second non-native species, the smallmouth bass M. dolomieu and its hybrids with Bartram's bass.  Bartram’s bass is a species of highest conservation concern in South Carolina and a priorirty species in the National Fish and Wildlife Foundation's Native Black Bass Initiative.  Conservation actions directed at this species and its native stream habitats will need to consider the establishment of non-natives in the drainage, and their potential to impact tributary populations over time.