Genetic characterization of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, in the Edisto River, South Carolina and identification of genetically discrete fall and spring spawning

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Once widely abundant, most subpopulations of the endangered Atlantic sturgeon are now estimated to be only 1–10% of their historical levels. The Edisto River has been sampled for a long period and extensively for juvenile Atlantic sturgeon from separate spring- and fall-spawned cohorts. Our objectives are to characterize the genetic diversity, stability, adaptive potential, and potential genetic structure of Atlantic sturgeon in the Edisto River and to identify any past bottlenecks experienced by this species, as well as to conduct forward simulation modeling of the population under multiple population trajectories. Our results indicate that fall- and spring-spawned Atlantic sturgeon in the Edisto River are genetically distinct (overall $${{F}_{ST}}$$ = 0.092) with little gene flow or admixture between groups, both of which are diverse from a neutral genetic marker standpoint. Genetic diversity of both groups is on the higher end of published population diversity values. A lack of inbreeding and recent bottlenecks also bode well for these two groups of sturgeon, although future projections indicate a loss of allelic richness and genetic diversity even with population stability. Our effective population size estimates are moderate compared to published estimates for other Atlantic sturgeon populations. The most significant finding of our research is the genetic distinctness of the fall- and spring-spawned Atlantic sturgeon in the Edisto River, which may have several important ramifications for management of the species, including re-evaluating the demarcation of distinct population segments.