What are the threats to shark populations in Indonesia?

Sembiring, A., Pertiwi, N. P. D., Mahardini, A., Wulandari, R., Kurniasih, E. M., Kuncoro, A. W., & Carpenter, K. E. (2015). DNA barcoding reveals targeted fisheries for endangered sharks in Indonesia. Fisheries Research, 164, 130-134.

Sharks form an integral part of marine ecosystems, but unfortunately their populations are in decline. Shark fisheries are a contributing factor, combined with certain traits sharks have, such as long gestation periods and late maturity. The study investigated the sustainability of shark fishing in Indonesia by DNA barcoding of shark fins. The results indicate that many of the reef sharks that used to thrive in Indonesia have become a rare occurrence, and that fisheries specifically target some of these endangered species.

Even though shark fishing is big business in Indonesia, there is a lack of available data on catch rates.  This is partly due to fisheries operating throughout the whole of Indonesia’s expansive territory. Another problem is the difficulty of identifying the species that dried shark fins belong to, as the fins are often removed at sea. This study used DNA barcoding to overcome this problem, and has aimed to form a foundation where shark fishing and trade can be closely monitored.

Between 2012 and 2014, a team of researchers collected 582 shark fins from fish markets and shark fin traders across Indonesia. They extracted DNA from these fins, after which the species’ identity could be established by using the Genbank and Barcode of Life Data Systems databases.

Large quantities of shark fins came from endangered, near threatened or vulnerable species

The results found that over 50% of the sampled shark fins were from just five different species. Worryingly, the species that fall into this category are different from the species that were identified in previous research. In 2009, a published study found that the most commonly fished species were dusky, spot-tail, blue and scalloped hammerhead sharks. In contrast, in this more recent study spot-tail sharks contributed to only 6.7% of the sample, while only one dusky shark was identified. Only 7.2% of the sample came from species of ‘least concern’.

Worryingly the scalloped hammerhead (categorised as endangered) accounted for over 10% of the sample. The researchers suggest that fisheries specifically target this species, and potentially other endangered of threatened species. Another indication of heavy overfishing is the low number of reef sharks that were identified among the sample. In Indonesian waters, most shark fishing occurs in areas were reef sharks typically thrive, in tropical waters and near coral reefs. A large proportion (83%) of the fins belonged to oceanic sharks, which suggests.

In conclusion, the research indicates that current shark fishing practices in Indonesia are unsustainable, this is not only a threat to vulnerable shark species, but to entire ecosystems. Research and initiatives exploring how to enforce current regulation would be helpful to prevent a further decline or even extinction of certain species of sharks in Indonesia.

World Animal Protection’s view

This study provides a valuable insight into Indonesian shark fishery practices. The research demonstrates that overfishing is an imminent threat to the conservation of several shark species and the ecosystems they are part of. Ecosystems are not only tremendously important as a natural resource, but also as a source of food and income for people, therefore enforcement of regulations are essential.