Distribution and New Records of the Bluntnose Sixgill Shark, (Hexanchiformes: Hexanchidae), from the Tropical Southwestern Atlantic.

The bluntnose sixgill shark, , is a widely distributed demersal species found in tropical and temperate waters of the Pacific, Atlantic, and Indian Oceans, inhabiting continental shelves and slopes, islands, and mid-ocean ridges at depths ranging from 200 to 1100 m. In the Southwestern Atlantic, this species has been recorded from northeastern to southern Brazil, Argentina, and Uruguay. Despite this, the known distribution of this species in the Southwestern Atlantic is very patchy and, in some cases, still mostly ignored in the literature, such as in northeastern Brazil.

Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north-eastern coast: Habitat use and resource partitioning.

Understanding the ecological role of species with overlapping distributions is central to inform ecosystem management. Here we describe the diet, trophic level and habitat use of three sympatric stingrays, Hypanus guttatus, H. marianae and H.

Mercury concentrations in coastal Elasmobranchs (Hypanus guttatus and Rhizoprionodon porosus) and human exposure in Pernambuco, Northeastern Brazil.

Elasmobranchs are long-lived predatory fish that show high Hg concentrations generally reflecting environmental levels, notwithstanding they are widely consumed in Brazil increasing Hg exposure to humans. This study reports on Hg concentrations in largely consumed sharks (Rhizoprionodon porosus) and rays (Hypanus guttatus) from the Pernambuco coast, NE Brazil and the risk associated with their consumption. Muscle tissue concentrations of Hg in H.

Reproductive biology of the whitespotted eagle ray Aetobatus narinari (Myliobatiformes) captured in the coast of Paraíba and Pernambuco, Brazil.

The present study analysed aspects of reproductive biology based on macroscopic and microscopic structures of whitespotted eagle ray Aetobatus narinari captured by artisanal fishing off the coast of Paraíba and Pernambuco (7° 30' S, 34° 49' W; 7° 47' S, 34° 51' W), northeast Brazil. Of the 71 individuals in the sample, 55% were female (disc width - W : 532-1698 mm) and 45% were male (W : 442-1410 mm). The body size at which 50% of the individuals are mature (W ) for males was 1155.

Habitat use and nursery evaluation for the longnose stingray Hypanus guttatus (Bloch & Schneider, 1801) using vertebral microchemistry.

Here, we use vertebral microchemistry to investigate the habitat use patterns of the longnose stingray Hypanus guttatus in the northern and northeastern regions of Brazil, and to evaluate the existence of potential nurseries of the species. Samples were collected in Maranhão, Rio Grande do Norte and Pernambuco states between 2008 and 2019. Trace element concentrations of Ba:Ca, Mg:Ca, Mn:Ca and Sr:Ca in vertebrae were determined through laser ablation inductively coupled plasma mass spectrometry.

From plentiful to critically endangered: Demographic evidence of the artisanal fisheries impact on the smalltail shark (Carcharhinus porosus) from Northern Brazil.

The smalltail shark, Carcharhinus porosus, was the most abundant elasmobranch species in fisheries off Brazil's northern coast (BNC) in the 1980s, but its population has been declining since the 1990s. For this reason, a demographic analysis is necessary to determine the extent of this decline and the fishing effect on the BNC's population. Therefore, we performed a stochastic demographic analysis of the population in the BNC, and considered its global center of abundance.

Shape analysis of shark jaws as a tool to identify species involved in incidents with humans.

Shark incidents in Recife, Pernambuco state (Brazil), are registered since 1992. The occurrence of those events is in a relatively small area of urban beaches of about 30 km long, making up one of the world's highest indices of shark incidents per unit of area, totaling 64 casualties, of these 24 were fatal. To mitigate shark incidents, the knowledge on shark species involved is crucial given that each species has specific usage of the habitat and dissimilar feeding strategy.

Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil.

We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.

Analysis of the supply chain and conservation status of sharks (Elasmobranchii: Superorder Selachimorpha) based on fisher knowledge.

Increasing fishing effort has caused declines in shark populations worldwide. Understanding biological and ecological characteristics of sharks is essential to effectively implement management measures, but to fully understand drivers of fishing pressure social factors must be considered through multidisciplinary and integrated approaches. The present study aimed to use fisher and trader knowledge to describe the shark catch and product supply chain in Northeastern Brazil, and evaluate perceptions regarding the regional conservation status of shark species.

Age, Growth and Spatial Distribution of the Life Stages of the Shortfin Mako, Isurus oxyrinchus (Rafinesque, 1810) Caught in the Western and Central Atlantic.

The shortfin mako (Isurus oxyrinchus) is a highly migratory pelagic shark that preferentially inhabits oceanic regions in practically all oceans. The wide distribution range of this species renders it susceptible to coastal and oceanic fishing operations. The International Union for Conservation of Nature (IUCN) and the International Commission for the Conservation of Atlantic Tunas (ICCAT) consider this species to be highly vulnerable, especially due to its biological parameters, which are different from those of other sharks that occupy the same niche (e.

Trends in the exploitation of South Atlantic shark populations.

Approximately 25% of globally reported shark catches occur in Atlantic pelagic longline fisheries. Strong declines in shark populations have been detected in the North Atlantic, whereas in the South Atlantic the situation is less clear, although fishing effort has been increasing in this region since the late 1970s. We synthesized information on shark catch rates (based on 871,177 sharks caught on 86,492 longline sets) for the major species caught by multiple fleets in the South Atlantic between 1979 and 2011.

Multifractal properties of a closed contour: a peek beyond the shape analysis.

In recent decades multifractal analysis has been successfully applied to characterize the complex temporal and spatial organization of such diverse natural phenomena as heartbeat dynamics, the dendritic shape of neurons, retinal vessels, rock fractures, and intricately shaped volcanic ash particles. The characterization of multifractal properties of closed contours has remained elusive because applying traditional methods to their quasi-one-dimensional nature yields ambiguous answers. Here we show that multifractal analysis can reveal meaningful and sometimes unexpected information about natural structures with a perimeter well-defined by a closed contour.