Determination of Geographical and Seasonal Variations of Heavy Metals in Swordfish (Xiphias gladius) and Yellowfin Tuna (Thunnus albacares)

Bioaccumulation of heavy metals in marine fish is a major concern worldwide and it leads to some economical burdens for the tropical fish exporters. However, data is yet to be unavailable in Sri Lanka in this regard. Hence this study was conducted to explore geographical variation of heavy metal accumulation in the Swordfish (Xiphias gladius) and Yellowfin tuna (Thunnus albacares) as they play a predominant role in the export fish market in Sri Lanka. Secondary heavy metal analysis data of Mercury, Led, Arsenic and Cadmium were collected from two major fish export companies in Sri Lanka during the period of 2015 to 2017. Particular points were traced with the aid of log sheets and heavy metal variations were mapped against fish species and heavy metal concentrations by using QGIS software. Heavy metal analysis data were concentrated between 64 to 70 longitudes and 0 to 8 latitudes, 76 to 80 longitudes and 0 to 8 latitudes, 88 to 92 longitudes and 14 to18 latitudes and 82 to 90 longitudes and 6 to 14 latitudes. Heavy metals such as Cd, As and Pb were not detected in the fish samples. Mercury was the major heavy metal accumulated among the tested and high concentration was detected in Swordfish. Mercury accumulation was highest in longitudes between 64 to 70 and latitudes of 0 to 8.This shows serious health issues that are challenging to humans and provides clear evidence on marine pollution. It is recommended to prevent fishing in these particular areas. Proactive measures and techniques need to be applied to fix safe limits of heavy metals in these natural aquatic ecosystems and protect the organisms in the environment.