Restocking has been practiced by hatcheries in some hydrographic basins of Brazil, such as the São Francisco River basin, where the captive-broodstock strategy has often been adopted. In such cases, breeders are replaced by their offspring across successive generations, potentially negatively affecting fitness and genetic diversity. One of the restocked species of this river is the catfish Lophiosilurus alexandri, which has been subjected to restocking over the past two decades. Despite such a long activity, no monitoring of the genetic diversity of these hatcheries’ broodstocks or how genetically related these are to their wild conspecifics has been carried out. This work aimed to genetically evaluate three hatcheries broodstocks of L. alexandri intended to restocking actions in the São Francisco River.
A total of 85 individuals were sampled, 55 individuals from three hatcheries, located in the submiddle and lower São Francisco River, and 30 wild animals from the submiddle stretch of this river. DNA was extracted using the phenol: chloroform protocol and subsequently, the control region (d-loop) of mitochondrial DNA was amplified with modified primers described by Pereira (2015). After sequencing and trimming, d-loop fragments of 425 bp were obtained. Thirty-two polymorphic sites were detected, of which eight were singletons and 24 were parsimoniously informative, all with two variants.
All hatcheries showed extremely low genetic diversity compared to the wild individuals (Figure 1, Table 1), with one of them having a single fixed haplotype. This highlights how poorly planned hatchery-based restocking can erode genetic diversity and threaten wild population.