Streamlined Genetic Identification of Ridgeback Sharks for Fisheries Management and Conservation

The burgeoning market for shark products, including high demand for shark fins, has raised widespread concerns about ecologically harmful exploitation of many shark species, and prompted calls for better management and conservation of sharks on a species-specific basis. Despite the desired goal of species-specific management, the U.S. Atlantic shark fishery is currently managed on the basis of species groups mainly because of difficulties identifying many of the requiem sharks (family Carcharhinidae) common in the fishery. We report a highly streamlined, rapid multiplex PCR method for identifying ridgeback carcharhinid shark carcasses and other body parts to species level. Our multiplex PCR assay comprises eight species-specific nested in between two universal primers simultaneously to discriminate the seven ridgeback sharks (night [ Carcharhinus signatus ], dusky [ C.obscurus ], Caribbean reef [ C. perezi ], sandbar [ C. plumbeus ], bignose [ C. altimus ], silky [ C. falciformis ], and tiger [ Galeocerdo cuvier ]) in U.S. and global commercial fisheries. The primers are designed based on fixed, species-specific variations in the nuclear ribosomal ITS2 locus. Assessment of intra-specific DNA sequence variability in this locus on a global scale indicates extremely high conservation within species, making the ITS2 locus very useful for potential shark DNA barcoding applications. Use of this assay to screen fins from the Hong Kong market reveals the presence of fins from most of these ridgeback species in the international fin trade.