Sharks and their relatives, including skates, rays and chimaeras, are a small, evolutionarily conservative group, comprising approximately 1000 species that have functioned successfully in diverse ecosystems for 400 million years. Despite their evolutionary success, a number of sharks are threatened with extinction as a result of human activity.
Sharks are highly vulnerable to overexploitation leading to population depletion due to their life history strategies. They are predominantly characterised as long-lived, slowgrowing and producing few offspring. These characteristics are associated with low productivity, close stock recruitment relationships, and long recovery times in response to overfishing. Other threats such as pollution and habitat destruction pose serious issues for sharks. In response to this issue, Professor Takaomi Arai, a professor of the Environmental and Life Sciences programme, and a team have started landing port survey to understand the biology and ecology of sharks in South China Sea since October 2014.
In the study, they found a number of young-of-the-year (born within the reproductive year) sharks just after they were born. Five of 11 sharks, Carcharhinus sealei, Loxodon macrorhinus, Rhizoprionodon acutus, Hemigaleus microstoma and Sphyrna lewini, were in the ranges of or even less than the lengths at birth that have been reported previously (pictured). The results suggest that these sharks bore just before fishing and landing. S. lewini and H. microstoma are categorised as endangered and vulnerable species, respectively and other sharks are categorised as near threatened. Thus, current fishing methods might lead further critical levels such as extinct in the future.
The team deducted that an improvement in the species selectiveness of fishing gear is needed to protect and conserve sharks in the area. Furthermore, the study is currently ongoing and the researchers plan to monitor activities on shark catch and trading after the implementation of the law in Brunei Darussalam.
In 2013, Brunei Darussalam officially banned the catch and landing of all shark species from the waters of Brunei Darussalam and their sales in the domestic market as well as a ban on the importation and trade of shark products. Brunei Darussalam has become the first Asian country to adopt a nationwide shark fin ban and it completely effective from January 2014, which routine checks on establishments were conducted to ensure the ban is followed.
However, the sharks and rays landings that constitute a part of the demersal fishery occur throughout the Malaysian waters of the South China Sea, from the coasts to the edges of its exclusive economic zone. Sharks are not targeted by fishers but are caught together with other commercially important species. Although a few fisheries and taxonomical information of sharks from South China Sea are available, biological and ecological studies are at rudimentary level.
Professor Takaomi Arai, who recently joined UBD at the Faculty of Science, teaches in the Environmental and Life Sciences programme. His research focus areas include Environmental Science and Pollution, Aquatic Organisms, and Marine Biology and Ecology.
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