Looking for sweet home in captive waters: population genetic structure of the introduced Arapaima in Bolivia

Invasive aquatic species are increasing globally due to factors related to globalization and accelerated trade between regions. Introductions generally cause disturbance at the ecological level with subsequent local and/or regional socioeconomic changes. The paiche Arapaima, one of the largest fish in the Amazon, was introduced via Peru into Bolivia in the 1960s, and has generated significant changes in Amazonian fisheries and fish value chains. In recent years, it has been proposed that genus Arapaima is composed by different species distributed along the Amazon Basin. It is unknown if the individuals introduced in Bolivia corresponded to a single species, and if they belonged to a single population. The present study evaluated the genetic variability of the paiche in the Bolivian Amazon Basin (sub-basins of the Orthon, Madre de Dios and Beni rivers) to determine identity (NADH and CO1 – mtDNA) and population structure (microsatellites – nDNA). The mtDNA and nDNA results suggested that all analyzed individuals belong to the same entity, which is made up of three populations corresponding to the geographic sub-basins according to the microsatellite analysis. The genetic distance between populations was not significantly related to the genetic distance between collection sites. It is proposed that the set of individuals (founder population) of the species in Bolivia was composed of different populations, which crossed a bottleneck and dispersed in search of environmental conditions similar to those present in the habitats from which they were extracted in their natural area of distribution. Planning for the sustainable use of the species by fisheries should consider that there are different populations in the Bolivian sub-basins, and recruitment seems to depend on exchanges between nearby surrounding aquatic habitats rather than between sub-basins.