Genetic diversity and structure of the commercially important native fish pacu (Piaractus mesopotamicus) from cultured and wild fish populations: relevance for broodstock management

Pacu (Piaractus mesopotamicus) is one of the most important Neotropical freshwater fish species produced by aquaculture in South America. This study is the first attempt to inquire about aquaculture stocks in Argentina regarding genetic diversity and structure. Neither genetic characterization nor pedigree records are available for pacu stocks in farms in Argentina. The presence of hybrids in both natural environment (Lower Paraná River) and farms has not been evaluated yet at the southern region of pacu distribution. Genetic characterization of pacu broodstocks, corresponding to 8 farms, and wild individuals from four areas at Lower Paraná River was performed. Pacu hybrids were not detected neither in wild nor in farm stocks analyzed. In general, similar levels of genetic diversity were observed between cultured and wild fish populations. Global genetic differentiation (Fst = 0.055) indicated a low level of structure and AMOVA showed that genetic variation was mostly within populations. Reduced contemporary effective population size (Ne) was observed, and probably reflects the bottleneck by founder effect in farmed fish populations. Moreover, kinship analysis showed that in fish farms, on average, 43.00% of the individuals were genetically related, whereas in wild population it was 36.40%. We recommend that broodstock management practices, such as using large Ne, single pair mating, precise records, and tagging of brood fish, should be implemented to avoid unintentional mismanagement.Fil: Del Pazo, F.. Universidad Nacional de Rosario; ArgentinaFil: Sánchez, Sebastián. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Posner, Victoria. Universidad Nacional de Rosario; ArgentinaFil: Sciara, Andrés A.. Universidad Nacional de Rosario; ArgentinaFil: Arranz, Silvia Eda. Universidad Nacional de Rosario; ArgentinaFil: Villanova, Gabriela V.. Universidad Nacional de Rosario; Argentin

Haplotypes traceability and genetic variability of the breeding population of pacu (Piaractus mesopotamicus) revealed by mitochondrial DNA

The main objective of this study was to estimate the genetic diversity levels and haplotype traceability in pacu Piaractus mesopotamicus from the breeding program located in Brazil by analyses of the mitochondrial DNA control region (mtDNA). Moreover, broodstocks from eight commercial fish farms were used for comparative evaluation, four from Brazil (Br1-Br4) and four from Argentina (Ar1-Ar4). The descriptive results revealed 47 polymorphic sites and 51 mutations, which evidenced 34 haplotypes. Ten haplotypes were shared among fish farms and 24 were exclusive. The nucleotide diversity (π) ranged from 0.00031 to 0.01462 and haplotype diversity (Hd) from 0.125 to 0.868. The analysis of molecular variance (AMOVA) indicated high structure present in the analyzed stocks (FST = 0.13356 and ФST = 0.52707). The genetic diversity was high in most of the commercial broodstocks, especially those from Brazil. We observed seven haplotypes in the genetic breeding population, of which four were exclusive and three shared among the commercial fish farms. The genetic diversity was moderate (π = 0.00265 and Hd = 0.424) and considered appropriated for this breeding population of pacu. Our results provide support for the genetic diversity maintenance and mtDNA traceability of pacu commercial broodstocks.Fil: de Freitas, Milena V.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; BrasilFil: Ariede, Raquel B.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; BrasilFil: Hata, Milene E.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; BrasilFil: Mastrochirico Filho, Vito A.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; BrasilFil: del Pazo, Felipe. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Villanova, Gabriela Vanina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Mendonça, Fernando F.. Universidade Federal de Sao Paulo; BrasilFil: Foresti, Fábio Porto. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Hashimoto, Diogo T.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasi