The loss of variability in farmed populations and the risks of interactions with wild populations support the need for the genetic monitoring of species farmed throughout the world. In Brazil, the tambaqui is the most widely farmed native fish species. Despite this, there are no data on the pedigree of the farmed stocks, and the potential for interactions with wild populations in the Amazon basin has raised concerns with regard to the genetic variability of these stocks. The present study analysed sequences of the mitochondrial Control Region and 12 microsatellites to characterize the genetic variability of seven historically important commercial tambaqui breeding centres located in four different regions of Brazil, and compared these sequences with those obtained from individuals collected from a wild population. High levels of genetic diversity were found in the wild population, whereas genetic diversity was reduced in both markers in most captive populations, except for the broodstock located near the Amazon River. High FST and DEST indices were recorded between the wild population and most of the captive stocks analysed. The drastic reduction in genetic diversity found in most captive stocks and the difference between these stocks and the wild population may have been the result of the small size of the founding populations and the absence of breeding management. The renewal of the broodstocks and the application of breeding management techniques are recommended. In the Amazon region, in addition, the use of broodstocks that are genetically very different from local wild populations should be avoided.

The present study evaluated the genetic variability of the broodstocks of tambaqui hatcheries in the Brazilian state of Pará. Samples were obtained from the caudal fin of 110 broodstocks from one hatchery in each of four municipalities (Santarém, Peixe-Boi, Breu-Branco, and Ulianópolis), representing all the individuals of each hatchery stock. The samples were genotyped using the multiplex system microsatellite markers. Data were used to calculate observed and expected heterozygosity, number of alleles per locus, and allelic richness. The effective population size and inbreeding coefficient were also calculated. The genetic differentiation between populations was evaluated by using F ST , and population structuring by the most likely number of genetically homogenous populations and Unweighted Pair Group Method (UPGMA); the arithmetic means were based on Nei's. The indices indicated a loss of genetic variability in the broodstocks from Ulianópolis, Peixe-Boi, and Breu-Branco in comparison with wild tambaqui populations, although this was not apparent in the Santarém stock. A moderate level of genetic differentiation was found among the tambaqui broodstocks based on the F ST estimates, which were reinforced by the structuring found in the Bayesian analysis and UPGMA. This reflects the domestication process, given that no such structuring is found in natural tambaqui populations. This moderate genetic differentiation associated with the loss of genetic variability found in the four tambaqui broodstocks from the state of Pará provides important insights for the development of future programs of genetic improvement, as well as the conservation of the genetic diversity of these stocks.

Colossoma macropomum is the second largest scaled fish of the Amazon. It is economically important for commercial fisheries and for aquaculture, but few studies have examined the diversity and genetic structure of natural populations of this species. The aim of this study was to investigate the levels of genetic variability and connectivity that exist between three natural populations of C. macropomum from the Amazon basin. In total, 247 samples were collected from the municipalities of Tefé, Manaus, and Santarém. The populations were genotyped using a panel of 12 multiplex microsatellite markers. The genetic diversity found in these populations was high and similar to other populations described in the literature. These populations showed a pattern of high gene flow associated with the lack of a genetic structure pattern, indicating that the number of migrants per generation and recent migration rates are high. The values of the FST, RST, and exact test of differentiation were not significant for pairwise comparisons between populations. The Bayesian population clustering analysis indicated a single population. Thus, the data provide evidence for high genetic diversity and high gene flow among C. macropomum populations in the investigated region of the Amazon basin. This information is important for programs aiming at the conservation of natural populations.

The present study analyzed the genetic variability and structure of farmed tambaqui in the Brazilian state of Pará, and provided basic information that can be used for the development of programs of monitoring and management of genetic resources in the aquaculture operations of northern Brazil. A total of 216 individuals were sampled from tambaqui farms in Pará. Genotyping was based on a multiplex set of 10 tri-and tetra-nucleotide microsatellite markers. The data were used to calculate genetic diversity indices, expected and observed heterozygosity, the number of alleles per locus, allelic richness, and inbreeding coefficient. Genetic structure was verified using D EST and R ST , the genetic signature, and Bayesian analysis. The results showed that the tambaqui farms surveyed have suffered a significant loss of genetic variability, and that they are genetically structured, forming two clusters, one encompassing the farms in western Pará, and the other including the farms from the northeast and southeast regions of the state. These finding provide fundamental insights for the development of effective strategies that will help guarantee productivity and the quality of the tambaqui farms of northern Brazil, and provide a database for the upgrading of the genetic variability of these populations. This study indicated the need for hatcheries in southeastern and northeastern Pará to amplify or renew their breeding stocks, in order to avoid the significant loss of genetic diversity in the tambaqui farms of these regions.

A broad panel of potentially amplifiable microsatellite loci and a multiplex system were developed for the Amazonian symbol fish species Arapaima gigas, which is currently in high danger of extinction due to the disorderly fishing exploitation. Several factors have contributed to the increase of this threat, among which we highlight the lack of genetic information about the structure and taxonomic status of the species, as well as the lack of accurate tools for evaluation of the effectivity of current management programs. Based on Arapaima gigas’ whole genome, available at the NCBI database (ID: 12404), a total of 95,098 unique perfect microsatellites were identified, including their proposed primers. From this panel, a multiplex system containing 12 tetranucleotide microsatellite markers was validated. These tools are valuable for research in as many areas as bioinformatics, ecology, genetics, evolution and comparative studies, since they are able to provide more accurate information for fishing management, conservation of wild populations and genetic management of aquaculture.

BACKGROUND In recent years, tracing of alimentary produce of animal origin has become increasingly important, for economic, food safety and ecological reasons. The tambaqui, Colossoma macropomum, is the native fish most farmed in Brazil. The reliable identification of the origin of tambaquis (wild or farmed) offered for sale to the general public has become necessary to satisfy regulatory norms and uphold consumer confidence. Molecular methods based on the analysis of DNA sequences have often been used to evaluate the potential for tracing farmed fish, given their reliability and precision. RESULTS Full likelihood and Bayesian approaches proved to be the most efficient for the identification, respectively, of individuals and populations for most of the fish sampled from seven hatcheries and one wild stock. The exclusion method and genetic distances were the least effective approaches for the identification of individuals and populations. The Bayesian method identified correctly more than 99% of the fry from most stocks, except those of the Santarém hatchery and River Amazon wild stock, which presented the best results for individual identification. CONCLUSIONS The identification of populations was effective for most hatcheries, although the identification of individuals from most stocks was hampered by the reduced genetic variability. © 2018 Society of Chemical Industry

ABSTRACT. Genetic variability is one of the important criteria for species conservation decisions. This study aimed to analyze the genetic diversity and the population differentiation of two natural populations of Arapaima gigas, a species with a long history of being commercially exploited. We collected 87 samples of A. gigas from Grande Curuai Lake and Paru Lake, located in the Lower Amazon region of Amazônia, Brazil, and genotyped these samples using a multiplex panel of microsatellite markers. Our results showed that the populations of A. gigas analyzed had high levels of genetic variability, which were similar to those described in previous studies. These two populations had a significant population differentiation supported by the estimates of F ST and R ST (0.06), by Bayesian analysis (K = 2), and by population assignment tests, which revealed a moderate genetic distance.

The Amazonian symbol fish Arapaima gigas is the only living representative of the Arapamidae family. Environmental pressures and illegal fishing threaten the species’ survival. To protect wild populations, a national regulation must be developed for the management of A. gigas throughout the Amazon basin. Moreover, the reproductive genetic management and recruitment of additional founders by aquaculture farms are needed to mitigate the damage caused by domestication. To contribute to the sustainable development, we investigated the genetic diversity of wild and cultivated populations of A. gigas and developed a panel composed by 12 microsatellite markers for individual and population genetic tracing. We analyzed 368 samples from three wild and four farmed populations. The results revealed low rates of genetic diversity in all populations, loss of genetic diversity and high inbreeding rates in farmed populations, and genetic structuring among wild and farmed populations. Genetic tracing using the 12 microsatellite markers was effective, and presented a better performance in identifying samples at the population level. The 12-microsatellite panel is appliable to the legal aspects of the trade of the A. gigas, such as origin discrimination, reproductive genetic management by DNA profiling, and evaluation and monitoring of genetic diversity.