REVIEW AND ANALYSIS OF MERCURY LEVELS IN BLUE MARLIN (Makaira nigricans, Lacepede 1802) AND SWORDFISH (Xiphias gladius, Linnaeus 1758)

Abstract

Mercury in the environment comes from natural processes and industrial activities. The inorganic form associates with the organic matter resulting on methylmercury (MeHg), the most toxic form to man. Mercury occurs in fishes mostly in organic form, the methylmercury. The billfishes appear to have high mercury levels because they are large predators that occupy top levels in the trophic chain. The mercury biomagnificates through the trophic chain and reaches high concentrations in top predators. The present study summarized the information about mercury levels in billfishes available in the literature, with emphasis on swordfish and blue marlin and made an analysis of data from several studies using the multivariate technique Agglomerative Hierarchical Cluster (AHC). The total mercury (THg) ranged from 0.7g/g to 12.2g/g in blue marlin and from 0.04g/g to 5.1g/g in swordfish, with data from 121 blue marlin specimens and 354 of swordfish. While a large part of the mercury content of the blue marlin was above 0.5g/g allowed by WHO, the specimens of swordfish summarized on the present study showed generally lower values within or slightly above this limit, but the swordfish is still consumed nowadays, and large amounts consumed oftentimes may represent a risk to human health.