Status of Southeast Asia's marine sharks and rays

Beneath the surface: DNA barcoding of shark fins in Singapore

The global decline of shark populations, largely driven by overfishing to supply the shark fin trade, poses a significant threat to marine ecosystems. Southeast Asia, and particularly Singapore, is a key hub for the transit and trade of shark fins that contribute to the exploitation of these apex predators. Through the use of DNA barcoding techniques, this study aimed to determine what species of shark are involved in the Singapore shark fin trade. Fins were collected from markets, dried goods shops and traditional Chinese medicine halls throughout Singapore. In total, DNA was extracted from 684 fins collected in January 2024 and PCR amplification targeted a fragment of the mitochondrial COI gene for species identification. Results revealed fins from 24 species across 16 genera, with 19 species listed on CITES Appendices II, and 16 listed as threatened on the IUCN Red List (critically endangered = 2, endangered = 4, vulnerable = 10). The top five most frequently identified species were Carcharhinus falciformis, Galeorhinus galeus, Rhizoprionodon oligolinx, Sphyrna lewini and Rhizoprionodon acutus. Of these, four are listed on CITES Appendix II and four are listed as threatened on the IUCN Red List.

DNA barcoding continues to identify endangered species of shark sold as food in a globally significant shark fin trade hub

Shark fins are a delicacy consumed throughout Southeast Asia. The life history characteristics of sharks and the challenges associated with regulating fisheries and the fin trade make sharks particularly susceptible to overfishing. Here, we used DNA barcoding techniques to investigate the composition of the shark fin trade in Singapore, a globally significant trade hub. We collected 505 shark fin samples from 25 different local seafood and Traditional Chinese Medicine shops. From this, we identified 27 species of shark, three species are listed as Critically Endangered, four as Endangered and ten as Vulnerable by the International Union for Conservation of Nature (IUCN). Six species are listed on CITES Appendix II, meaning that trade must be controlled in order to avoid utilization incompatible with their survival. All dried fins collected in this study were sold under the generic term "shark fin"; this vague labelling prevents accurate monitoring of the species involved in the trade, the effective implementation of policy and conservation strategy, and could unwittingly expose consumers to unsafe concentrations of toxic metals. The top five most frequently encountered species in this study are Rhizoprionodon acutus, Carcharhinus falciformis, Galeorhinus galeus, Sphyrna lewini and Sphyrna zygaena. Accurate labelling that indicates the species of shark that a fin came from, along with details of where it was caught, allows consumers to make an informed choice on the products they are consuming. Doing this could facilitate the avoidance of species that are endangered, and similarly the consumer can choose not to purchase species that are documented to contain elevated concentrations of toxic metals.

Status of Southeast Asia's marine sharks and rays

In Southeast Asia, elasmobranchs are particularly threatened. We synthesized knowledge from the peer-reviewed and gray literature on elasmobranchs in the region, including their fisheries, status, trade, biology, and management. We found that 59% of assessed species are threatened with extinction and 72.5% are in decline; rays were more threatened than sharks. Research and conservation is complicated by the socioeconomic contexts of the countries, geopolitical issues in the South China Sea, and the overcapacity and multispecies nature of fisheries that incidentally capture elasmobranchs. The general paucity of data, funds, personnel, and enforcement hinders management. Reduced capacity in the general fishery sector and marine protected areas of sufficient size (for elasmobranchs and local enforcement capabilities) are among recommendations to strengthen conservation.