In the present study, five loci (mitochondrial and nuclear) were sequenced to determine the genetic diversity, population structure, and demographic history of populations of the yellowtail snapper, Ocyurus chrysurus, found along the coast of the western South Atlantic. O. chrysurus is a lutjanid species that is commonly associated with coral reefs and exhibits an ample geographic distribution, and it can therefore be considered a good model for the investigation of phylogeographic patterns and genetic connectivity in marine environments. The results reflected a marked congruence between the mitochondrial and nuclear markers as well as intense gene flow among the analyzed populations, which represent a single genetic stock along the entire coast of Brazil between the states of Pará and Espírito Santo. Our data also showed high levels of genetic diversity in the species (mainly mtDNA), as well a major historic population expansion, which most likely coincided with the sea level oscillations at the end of the Pleistocene. In addition, this species is intensively exploited by commercial fisheries, and data on the genetic structure of its populations will be essential for the development of effective conservation and management plans.

Red snappers (Lutjanus purpureus in Brazil and Lutjanus campechanus in USA and Gulf of Mexico) are both under clear effect of overfishing. Because of their high morphological similarity it has already been suggested that they could possibly be considered as a single species. To investigate the degree of similarity and the genetic structure of red snapper populations we constructed a common dataset of partial D-loop mtDNA sequences of L. purpureus from Brazil (Amapá, Pará and Maranhão) and L. campechanus from the Atlantic coast of the USA (Florida, Louisiana and Mississippi). Phylogenetic and population genetic analyses surprisingly depicted high similarity between L. campechanus and L. purpureus, compatible with the hypothesis of a single species of red snapper for the Western Atlantic Ocean. These preliminary but very curious findings open an important discussion regarding the legislation involved on the capture of this overexploited fish resources as well as regarding their taxonomy

The Caribbean Red Snapper (Pargo) Lutjanus purpureus is the most economically important snapper in Brazil, which is sold, among other forms, as frozen fillets. During the process of transformation into fillets there is the removal of the distinctive morphological traits, being able to favor the substitution by less valued species. In addition, there is no national legislation requiring the insertion of the specific name on the product label. However, according to a Normative Instruction (IN N ° 29/2015 MAPA) that correlates the common and specific names of the products destined to the national trade, in Brazil only L. purpureus and L. campechanus can be denominated “Pargo”. Thus, the DNA barcode tool was used to identify the fillets sold in north of Brazil, labeled “Pargo”, with the aid of sequences from the public and control databases. The results showed that among 142 fillets examined, 78% was identified as L. purpureus and 22% as Rhomboplites aurorubens, a snapper with low commercial value in the country, revealing commercial fraud. The molecular identification method successfully used in this study to authenticate fillets snappers may also be used by surveillance authorities in the quality control of processed fish products, towards ensuring consumer rights.

Molecular genetic techniques are an effective monitoring tool, but high-quality DNA samples are usually required. In this study, we compared three different protocols of DNA extraction: NaCl (saline); phenol-chloroform and commercial kit (Promega)—from three biological tissues of five individuals of Lutjanus purpureus under two methods of storage. The evaluated items included DNA concentration and purity, processing time and cost, as well as the obtaining of functional sequences. The highest average values of DNA concentration were obtained using the saline procedure and the commercial kit. Pure DNA was only obtained using the saline protocol, evaluated by the ratio of 260/280. The saline and phenol-chloroform protocols were the least expensive methods. The commercial kit costs are counterbalanced by the short time required. The procedure based on phenol-chloroform presented the worst results regarding DNA yield and the time required to perform all steps. The saline and commercial kit protocols showed similar results concerning the amount and quality of extracted DNA. Therefore, the final choice should be based on the available financial resources and the available time for carrying out each procedure of DNA extraction.

Elasmobranchs represent a well-defined group, composed of about 1,150 species inhabiting diverse aquatic environments. Currently, several of these species have been classified as threaten due to overexploitation. Therefore, we used DNA barcode to identify traded species of sharks and stingrays in the municipality of Bragança (Amazon coastal region), a major fishery landing site in northern Brazil. We collected a total of 127 samples labeled into 24 commercial nomenclatures over 1-year period. Twenty species were discriminated and 13 of them are recognized under some threatening status. In relation to sharks, Carcharhinidae showed the highest number of species, half of them classified as endangered, followed by hammerhead sharks (Sphyrnidae), with four species also regarded as threatened with extinction. The Rhinopteridae and Dasyatidae rays were the most abundant groups, with trade records of the following threatened species: Rhinoptera brasiliensis, Rhinoptera bonasus, Hypanus berthalutzae, and Fontitrygon geijskesi. It is noteworthy that threatened species of elasmobranchs have been frequently and regularly exploited because of inefficient fishery management policies. Therefore, effective inspection practices need to be incorporated in fisheries, including the use of DNA barcode to enable a reliable method of species authentication and to assure the proper commercialization.

The Caribbean snapper Lutjanus purpureus is a marine species fish commonly found associated with rocky seabeds and is widely distributed along of Western Atlantic. Data on stock delineation and stock recognition are essential for establishing conservation measures for commercially fished species. However, few studies have investigated the population genetic structure of this economically valuable species, and previous studies (based on only a portion of the mitochondrial DNA) provide an incomplete picture. The present study used a multi-locus approach (12 segments of mitochondrial and nuclear DNA) to elucidate the levels of genetic diversity and genetic connectivity of L. purpureus populations and their demographic history. L. purpureus has high levels of genetic diversity, which probably implies in high effective population sizes values for the species. The data show that this species is genetically homogeneous throughout the geographic region analyzed, most likely as a result of dispersal during larval phase. Regarding demographic history, a historical population growth event occurred, likely due to sea level changes during the Pleistocene.