Biodiversity and conservation of marine elasmobranchs in the extreme south of the Brazil, Southwestern Atlantic

Abstract

The extreme south of Brazil, Southwestern Atlantic, presents a vast and interesting history of elasmobranchs occurrence records. This is a transition zone between warm tropical waters cold regions, which reflects in the great species diversity, including rare occurrences and endemism. Therefore, the aim of this study is to describe the composition and conservation status of elasmobranchs that occurs in state of the Rio Grande do Sul, south Brazil, through a detailed literature review and review lists of species deposited in regional, national and international collections. In total, 94 species were recorded (60.6% of Brazil elasmobranch biodiversity and 8% of the world), with 11 new records compared to the most recent study, distributed into 10 orders and 30 families. A total of 58 species of sharks were listed, most of them belonging to the order Carcharhiniformes (41.4%), followed by Squaliformes (27.6%), and 36 rays mainly of the orders Rajiformes (50.0%) and Myliobatiformes (30.5%). Concerning their conservation status, 26.6, 38.3 and 45.8% of the species are threatened (CR, EN, VU), at the regional, national and international levels, respectively. The intense fishing effort may be the main responsible for these results. Resumption of landings monitoring, inclusion of local ecological knowledge of fishermen, taxonomic and molecular identification of carcasses, are suggested as mitigating strategies.