Total mercury levels in muscle tissue of swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) from the Mediterranean Sea (Italy)

This study was carried out to determine the current levels of total mercury in the muscle tissue of swordfish (Xiphias gladius) and bluefin tuna (Thun nus thynnus) caught in the Mediterranean Sea with the purpose of ascertaini ng whether the concentrations exceeded the maximum level fixed by the Europ ean Commission Decision. In addition, specimens of each species were divide d into different ranges of weight to investigate the influence of size on m ercury accumulation in order to provide data upon which commercial fishing strategies and marketing of swordfish and bluefin tuna may be based. Higher mean levels of total mercury were found in bluefin tuna (1.02 mug g(-1) we t wt) than in swordfish (0.49 mug g(-1) wet wt). In 4.3% of swordfish and i n 44.3% of bluefin tuna analyzed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 mug g(-1) wet wt). Besides, for bluefin tuna the total mercury level variability obse rved, due to size, suggests that there should be greater regulatory control by the authorities.