Identification and phylogenetic inferences on stocks of sharks affected by the fishing industry off the Northern coast of Brazil

Abstract

The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate. The main aim of the present study was to identify those shark species being exploited off northern Brazil, by using the 12S-16S molecular marker. For this, DNA sequences were obtained from 122 specimens collected on the docks and the fish market in Bragança, in the Brazilian state of Pará. We identified at least 11 species. Three-quarters of the specimens collected were either Carcharhinus porosus or Rhizoprionodon sp, while a notable absence was the daggernose shark, Isogomphodon oxyrhyncus, previously one of the most common species in local catches. The study emphasises the value of molecular techniques for the identification of cryptic shark species, and the potential of the 12S-16S marker as a tool for phylogenetic inferences in a study of elasmobranchs.

A Review of the Mitogenomic Phylogeny of the Chondrichthyes

“…acronotus were involved in a polytomy. The polytomic pattern within Carcharhinidae is probably related to the low-levels of intrinsic genetic variability of sharks (Figure 2) [47]. The results of the present study are consistent with those of other molecular phylogenies [10,13,17,24].…”

Why implement measures to conserve the diversity of Elasmobranchs? The case of the northern coast of Brazil

“…Molecular techniques based on sequences of mitochondrial (mtDNA) or nuclear DNA have been widely used in studies of population genetics (Cruz, 2013;Pinhal, 2010;Tavares et al, 2013;Veríssimo et al, 2012;Rodrigues-Filho, et al, 2009;Dudgeon et al, 2012;Palmeira et al, 2013). The regions of the mitochondrial genome most used for these studies include the cytochrome b (Cyt b) gene and the Control Region (CR), which has been used in a large number of population genetics studies of sharks Tavares et al, 2013).…”

Introductory Chapter: The Elasmobranchs as a Fishery Resource

“…Molecular identiication is now used widely in research on elasmobranchs, based on a variety of genetic techniques [14,32,[60][61][62][63][64]. The most widely used approach, which is both simple and efective and provides a good diagnosis of most animal taxa, is DNA barcoding [12], which is based on the analysis of a small fragment of the mitochondrial Cytochrome Oxidase subunit I (COI) gene of approximately 648 nucleotides.…”