Genetic diversity and structure in populations of Piaractus mesopotamicus

Inadequate genetic management of broodstock in fish farming can lead to a reduction in genetic diversity, negatively affecting key productive traits such as growth and weight gain. This study evaluated the genetic diversity and population structure of pacu (Piaractus mesopotamicus Holmberg, 1887) from two fish farms located in the states of Bahia and Ceará, Brazil, and compared them with a wild population from the Pantanal region (Mato Grosso), using inter-simple sequence repeat (ISSR) molecular markers. Eight ISSR primers were selected based on reproducibility and efficiency, generating a total of 134 fragments, of which 94.03% were polymorphic. The results revealed low genetic diversity within populations and high genetic differentiation among them (FST = 0.79), with the DNOCS stock showing higher genetic diversity than the other farmed populations. Analysis of molecular variance (AMOVA) indicated that most of the genetic variation was distributed among populations. Cluster analysis and principal coordinate analysis showed greater genetic similarity between the Bahia Pesca population and the wild population from Mato Grosso. These findings highlight the need for improved genetic management strategies in pacu aquaculture, including the introduction of genetically diverse broodstock, to enhance productive sustainability and conserve species´ the genetic resources.