Genetic variability and population structure of the bull shark, Carcharhinus leucas, in the western Atlantic using mitochondrial DNA markers

• Grant number: 13/22883-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2014
• Effective date (End): December 31, 2014
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Claudio de Oliveira
• Grantee: Tássia Oliveira Biazon
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Among sharks exploited by fisheries, circumglobal coastal species exhibit greater complexity in the assessment and monitoring of their populations due to their distributions in vast geographical areas. Among these, the bull shark, Carcharhinus leucas, occurs in all coastal states of Brazil, there are records of catches in the Amazon River and also within the Patos Lagoon/RS. This species inhabits waters of the continental shelf at a depth of about 150 m, but mostly less than 30 m, and often moves to estuarine and freshwaters, being one of the only shark species that can exist for long periods in freshwater and penetrates long distances in large rivers. Its occurrence in brackish and freshwater makes it more vulnerable to human impacts on the marine environment and on the other hand, makes it even have much more contact with humans than other species of large sharks. Currently, C. leucas in the third shark species most sought to obtain fins, being its registered fishing throughout the Brazilian coastal area. However, basic information for fisheries management, such as the characterization of population genetic structure, identification of the levels of variability, identification of possible geographical restrictions to gene flow, and the existence of local populations remain poorly known. These aspects are especially relevant for the regulation of fishing and the fishing industry, providing subsidies for the management and conservation of stocks. Considering the urgent need for sustainable control of fishing this study aims to characterize the population genetic structure of the bull shark in the Western Atlantic, covering an area between the United States and Brazil, using molecular markers of mitochondrial DNA. Such results may identify the possible population of the species boundaries and their levels of genetic variability, geographical distribution, migration patterns, reproductive stocks, and historical events, permitting the creation of proposals for sustainable management of these sharks. (AU)