Total and methylmercury in sardines Sardinella aurita and Sardina pilchardus from Tunisia

This paper reports concentrations of total mercury and methylmercury in mus cle, liver and gonads of two sardines (Sardinella aurita, n = 184 and Sardi na pilchardus, n = 87) from three coastal areas off Tunisia, Mercury concen tration in muscle and liver showed significant positive correlation with fi sh length (i.e. with age), The relative methylmercury concentration was hig h and constant in muscle (>85% MeHg), and was decreasing with age in liver (from 50% to 20%), which might reflect the existence of a slow demethylatio n process, From the geographic point of view, Hg concentration was similar in the northern and eastern areas (0.32 mu g g(-1) dw in muscle for Sardine lla aurita, 0.41 for Sardina pilchardus), but significantly lower in the so uthern zone (0.19 and 0.26, respectively, median values). Mercury concentra tion in the Tunisian sardines was twice to four times lower than in the nor thern Mediterranean Sea. (C) 1999 Elsevier Science Ltd, All rights reserved .