Total mercury, alkyl mercury and selenium concentrations in the muscle tissue of several species of pelagic sharks from northern Australian waters are reported. Mean mercury concentrations ranged between O .13 mg /kg for Carcharhinus brevipinna and 1. 94 mg/kg for C. amblyrhyn choides. Maximum values exceeded 1.5 mg/kg in nine of the species studied and the highest recorded concentration was 3.7 mg/kg for Sphyrna mokarran.
Mercury concentrations were highly dependent on the size of shark, a relationship that was adequately represented by the power function. Males of most of the species studied had significantly higher levels of mercury than females of similar size.