Stock structure of pallid sturgeon analyzed with microsatellite loci

Recovery efforts for the endangered pallid sturgeon (Scaphirhynchus albus) include supplementation of wild stocks with hatchery reared progeny. Identifying the extent of genetic stock structure, which has previously been detected in samples from the range extremes, will help to determine whether stock transfers might be harmful. DNA microsatellite genotypes were screened in pallid sturgeon from the upper Missouri River, lower Missouri River, middle Mississippi River and Atchafalaya River and analyzed using a combination of Bayesian model‐based and more traditional F‐statistic based methods to characterize genetic differentiation. Scaphirhynchus specimens were collected by researchers active in the recovery effort and genotypes were screened at 16 microsatellite loci. Because there is considerable genetic and morphological overlap between pallid sturgeon, shovelnose sturgeon, and their hybrids, a combination of morphological and genetic techniques were used to eliminate shovelnose and possible hybrids from the sample. Genetic differentiation was detected among samples (overall θ = 0.050, P = 0.001). Pairwise θ, genetic distances, and Bayesian assignment testing reveal that pallid sturgeon from the upper Missouri River are the most distinct group with pairwise comparisons of pallid sturgeon among all the remaining samples exhibiting lower θ values, higher genetic distances, and self assignment scores. Our results indicate that using local broodstock, when available, should be used for pallid sturgeon propagation. If local broodstock are not available, geographically proximate individuals would limit genetic differences between native and stocked individuals.