Abstract
The pacu (Piaractus mesopotamicus) is a Neotropical fish with remarkable productive performance for aquaculture. Knowledge of genetic resources in Neotropical fish is essential for their applications in breeding programs. The aim of this study was to characterize the genetic diversity of seven farmed populations of pacu which will constitute the basis for a broodstock foundation for coming breeding programs in Brazil. Analysis of one wild population (Paraná River) was used as a reference to compare genetic parameters in the farmed populations. The analyses were performed using 32 single-nucleotide polymorphisms (SNP) and 8 simple sequence repeat (SSR) markers. No significant differences in genetic diversity between populations estimated through the number of alleles and allelic richness, observed heterozygosity, expected heterozygosity, and minimum allele frequency were detected (p > 0.05). Low genetic diversity was observed in all farmed stocks and the wild population. Moreover, we detected low genetic structure when comparing farmed and wild populations for SNPs (FST = 0.07; K = 3) and SSRs (FST = 0.08; K = 2). Analysis of molecular variance (AMOVA) demonstrated that genetic variation was mostly within populations. Kinship analysis showed that most fish farms included related individuals at a proportion of at least 25%. Our results suggest that the basal broodstock for pacu breeding programs should be founded with individuals from different fish farms for higher genetic diversity and to avoid inbreeding risks.
Highlights
The pacu (Piaractus mesopotamicus) is a Characiform fish with a wide natural distribution throughoutLa Plata basin which covers an area over five South American countries: Brazil, Uruguay, Bolivia, Paraguay, and Argentina
The parameters of genetic variability for pacu populations determined by 8 simple sequence repeat (SSR) and 32 single-nucleotide polymorphisms (SNP)
The methodology for breeding programs is well established in model species of worldwide aquaculture [37]
Summary
The pacu (Piaractus mesopotamicus) is a Characiform fish with a wide natural distribution throughoutLa Plata basin which covers an area over five South American countries: Brazil, Uruguay, Bolivia, Paraguay, and Argentina. Wild populations of pacu are threatened by overfishing since this species is considered to have high commercial value, with large-scale catches occurring by industrial and recreational fisheries [1]. Genes 2019, 10, 668 catches of pacu represent 5% (11 thousand tons) of the total inland capture (243.8 thousand tons) [2], classifying it as a critically endangered species in Sao Paulo State in Brazil (Decree 56,031). In relation to aquaculture production, pacu is one of the most cultivated fish species in South America. In Brazil, pacu farming already represents the second largest harvest from fish production (about 21 thousand tons) among native species [3]. According to its productive characteristics, it is an omnivorous fish considered a gainful species for aquaculture due to its rapid growth and low-cost feeding habits [4]
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