FLSGP-X-03-014 C2
FLORIDA SEA GRANT COLLEGE PROGRAM
Rorida
TITLE: Efficient PCR-based identification of shark products in global trade: applications for the management and conservation of commercially important mackerel sharks Family Lamnidae!, thresher sharks Family Alopiidae! and hammerhead sharks Family Sphyrnidae!.
STUDENT: DEBRA ABERCROMBIE
CHAIRMAN: MAHMOOD SHIVJI - R/LR-B-54
DEPARTMENT: Oceanographic Center
INSTITUTION: NOVA SOUTHEASTERN UNIVERSITY
DEGREE: MASTER OF SCEINCES
DATE: DECEMBER 2003
Shark populations worldwide are suspected to be in severe decline due to domestic and international markets for trade in shark products, especially dried fins in Asian markets, and as a result of bycatch mortality in multi-species fisheries. The management of sharks on a species-specific basis has become imperative for shark conservation, particularly in regions where numerous species are heavily fished, because sharks with differing life-history characteristics respond differently to exploitation. However, many commercially exploited sharks are morphologically similar and not easily identifiable to the species level. This problem is exacerbated when it comes to identifying detached fins, processed carcasses logs!, filets or steaks at the dock or in trade. To address these species-identification problems and make available an accurate but practical, DNA-based forensic method for use in conservation and management, I have developed a highly streamlined genetic assay based on multiplex polymerase chain reaction PCR! and species-specific'primers derived from interspecific DNA sequence differences in the nuclear ribosomal internal transcribed spacer 2 ITS2! locus of sharks. This forensic assay allows accurate identification of body parts from ten shark species commonly exploited worldwide for their meat and/or fins. In this thesis, I report on the development and use of this assay in the form of two separate suites of species-specific PCR primers that can be used in a high-density multiplex format to achieve rapid and accurate species identification. Chapter 1 of this thesis describes a suite of species-specific primers and multiplex PCR assay that simultaneously identifies seven shark species: four species of mackerel sharks, i.e. shortfin mako lsurus oxyrinchus!, longfin mako Isurus paucus!, porbeagle Lamna nasus! and salmon Lamna ditropis!; and the three species of alopiid thresher! sharks, i.e. common thresher Alopias vulpinus!, bigeye thresher Alopias superciliosus! and pelagic thresher Alopias pelagicus!. The second species-specific primer suite, described in chapter 2, simultaneously identifies the three globally distributed and most commercially important species of hammerheads: the great hammerhead Sphyrna mokarran!, scallopedhammerhead Sphyna lewini! and the smooth hammerhead Sphyrna zygaena!. The species-specific PCR primers and forensic approach described here provide an efficient, straightforward technique that can be used in conservation and management relevant contexts where large volumes of samples need to be screened quickly.