The Levels of Mercury and Selenium in Blood of Tunas

Abstract

The levels of mercury and selenium in thirty blood specimens of two species of tunas, i.e., eighteen individuals of yellow fin Thunnus albacares and twelve individuals of big-eye Tlaunnus obesus, were presented.
Mercury level and the ratio of methyl mercury content (MeHg) to total mercury content (T-Hg) in the blood were lowest in yellow fin and highest in big-eye, respectively, as compared with those in the other tissues and organs previously reported. Both the mercury contents (T-Hg and McHg)in big-eye were extremely high compared with those in yellow fin, and those contents in both species did not tend to increase with the growth of the fish.
Selenium content (Se) in the blood was highest in all tissues and organs, and there was no significant difference in the high selenium levels between both species.
The molar ratio(Se/Hg)of Se to T-Hg in the blood was also highest in all tissues and organs, and correlated negatively with T-Hg in the olood of both species. From the correlation, it was observed that yellow fin and big-eye belong to the one region (low T-Hg and large Se/Hg) and to the other (high T-Hg and small Se/Hg), respectively.