Genetic evaluation of migratory fish: implications for conservation and stocking programs

Fish stocking programs have been implemented to mitigate the blockage of original riverbeds by the construction of hydropower dams, which affects the natural migration of fish populations. However, this method raises concerns regarding the genetic rescue of the original populations of migratory fish species. We present the first study to investigate the genetic diversity, population structure, and gene flow (migration) of the Neotropical migratory fish Prochilodus costatus in the Três Marias dam in São Francisco River basin, Brazil, using high-throughput genotyping and population genetics approaches. In total, 1,017 specimens were sampled from 12 sites during 4 hydrological years and from broodfish used in a fish stocking program, and genotyped with 8 microsatellite loci. The samples showed low genetic variability, with inbreeding and the presence of only four genetic pools; three pools were observed throughout the study region and the fourth was exclusive to one area in the Paraopeba R...