Genetic comparison of populations of Piaractus brachypomus and P. orinoquensis (Characiformes: Serrasalmidae) of the Amazon and Orinoco basins

Recently, the large migratory fishes of the family Serrasalmidae ( Piaractus brachypomus and P. orinoquensis ) were described as restricted to the Orinoco and Amazon basins. Both species provide important ecosystem services. They also are an important fisheries resource, which has caused that their populations have decreased in recent years. National fisheries policies still consider both species as one, which leads to inefficiencies in their management and conservation. The aim of this study was to genetically characterize these two species, using microsatellite and mitochondrial markers, and discuss the implication of these results for conservation and management. We found that both species have moderate genetic diversity and varied patterns of genetic distribution in the fluvial landscape. Piaractus brachypomus presented genetic diversity of A=6.5; He=0.72; Ho=0.67; Ĥ=1.000; ᴫ =0.0092, three management units related to the evolutionary process of the Amazon basin and the effective sizes of local populations were smaller compared to P. orinoquensis , which presented genetic diversity of A=6.1; He=0.66; Ho=0.55; Ĥ=0.968; ᴫ =0.010 and comprises only one management unit. These results demonstrate the need to design management policies that focus on species and geographically restricted populations.