Level of heavy metals in bamboo sharks (Chiloscyllium sp.) in straits of Malacca, Malaysia

Sharks which are the top predators in the ocean food chain are still high in demand as delicacies (shark meat) in restaurants despite the efforts to protect them. Anyhow, sharks accumulate a significant amount of metals in their bodies. Hence, a study was carried out to examine the presence and concentration of heavy metals (Cd, Cu, Pb and Zn) in bamboo sharks (Chiloscyllium), the most commonly landed species. A total of 43 Chiloscyllium samples were collected from the local fishermen in Lumut, Perak. In this study, the two edible tissue samples, namely the muscle and fins were dissected and analysed using inductively coupled plasma – mass spectrometry (ICP-MS) following a Teflon bomb closed digestion with HNO₃ acid. Based on the results, the concentration of heavy metals in muscle tissues arranged in a diminution order is Zn > Cu > Pb > Cd. Meanwhile, the concentration pattern of metals in fin tissues followed the Zn > Pb > Cu > Cd sequence. The average concentration of metals in the fin tissues was higher than that of muscle tissues. All metals examined were associated with the sharks' length and weight, whereby the findings also indicated that all metals exhibited positive correlation except for Pb concentration in muscle and Zn concentration in fin tissues. The Pollution Load Index (PLI) was used as the predictor to assess the contamination status in the tissue samples. The average PLI value calculated for the muscle and fin tissues ranged between 3.2 and 12.4, respectively. These values also indicated that the level of contamination is very much under control, hence, no monitoring is needed. Therefore, all findings from this study may be used as a reference for future studies, especially on the west coast of Peninsular Malaysia waters. Copyright © 2020 Malaysian Society of Analytical Sciences. All rights reserved.