Population structure of shortnose sturgeon Acipenser brevirostrum in Southeastern United States Rivers
McManus, Miranda Lynette
Strand, Allan E.
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The shortnose sturgeon is a federally endangered anadromous fish that inhabits waters along the eastern coast of North America. Census size for shortnose sturgeon in southeastern rivers has been estimated to be at or below one thousand individuals, likely due to anthropogenic impacts. An intensive stocking effort took place in the Savannah River from 1984 to 1992; however, less than 20 percent of these fish were tagged, making it nearly impossible to differentiate stocked fish from wild fish. Hatchery stocks have been captured in several other southeastern rivers, and it appears that fish that were stocked into the Savannah River emigrated and colonized other southeastern rivers. Unfortunately, because of the low numbers of tags, it is difficult to estimate the frequency of these dispersal events. In the National Marine Fisheries Service‚Äôs recovery plan for the species, a range-wide genetic assessment was considered high priority to assess any loss of adaptive genetic diversity among the watersheds. This study focuses on several southeastern rivers that have been affected by stocking and the subsequent straying. Microsatellite markers were used in this investigation to accomplish this assessment. Markers were treated as a set of binary phenotypes, and multivariate statistical techniques were used to cluster individuals and evaluate population differences. Pairwise comparisons showed statistical genetic differences among all of the watersheds. A priori clustering methods did not strongly support the differentiation between the Savannah and Ogeechee Rivers; they did, however, confirm that the Winyah Bay system houses a distinct population of shortnose sturgeon. The genetic markers used for this study are sufficient to analyze population differences in shortnose sturgeon. The primer set LS-68 is a useful tool for a cursory screening of fish.