MERCURY IN FISH FROM GOLD-MINING REGIONS IN THE UPPER CUYUNI RIVER SYSTEM, VENEZUELA

To evaluate aquatic effects of gold-mining operations, we determined t otal Hg concentrations in nine fish species taken in November-December 1992 from the Supamo-Parapapoy rivers, upper Cuyuni River system, Ven ezuela. Hg levels in axial muscle tissues ranged from <0.03 to 0.86 mu g/g wet weight (n=18). The highest value (0.86 +/- 0.26 [+/- SD]) was associated with a large (63-cm long) aimara (Hoplias macrophthalmus), a locally important food fish. Hg contents for liver tissue were 0.11- 2.57 mug/g (n=5); ovary tissue 0.09 mug/g (n=1); and gut contents (org anic mud) from a loricariid catfish 0.76 mug/g (n=1).