Fish Population Dynamics: Genetic Diversity of Longnose Gar, Sauger and Bluegill within the Ohio River

Presently, the Ohio River is segmented by twenty lock and dam structures (18 high-lift and 2 low head) along its 981 miles, some of which have been in place for close to 100 years. Dams can act as both geographic and genetic barriers by physically isolating fish populations, reducing genetic drift, and thereby genetic diversity. Genetic diversity underlies biodiversity which ensures the survival of a species and its adaptability to environmental changes. If genetic diversity is decreased then there is less for natural selection to act upon, potentially making a species vulnerable to extinction. The potential isolating effects of dams on populations of three relatively common fishes possessing variant life-history attributes within the Ohio River were investigated. To determine population isolation, 16S genetic markers were used for molecular analysis of longnose gar (Lepisosteus osseus), sauger (Sander canadensis) and bluegill (Lepomis macrochirus). Preliminary attempts at using the control region proved unsuccessful due to inconsistency with primers. DNA was extracted from fin clips of specimens collected from various navigational pools distributed throughout the entirety of the Ohio River proper.  A total of 200 sequences were obtained for the three species and results identified varying degrees of longitudinal population structure. This study attempts to measure the movement-inhibitive effects that navigational dams serve to fishes within a mid-continent great river. Secondary objectives of this study included providing baseline data for future population studies and adding Ohio River populations of these three species to the FISHBOL project.