Observations on metal concentrations in three species of shark (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstoni) from Southeastern Australian waters

Deep sea dog sharks (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstonii) were captured from the waters off western Victoria, Australia, in April and May 1998. The elements As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, Sr, and Zn were detected in the muscle tissue. The concentrations of Al, Ba, Be, Cr, Mo, Ni, Pb, and V were below the detection limits of the instrumental techniques employed (ICP-ES and GF-AAS). However, significant concentration differences between species were detected for As, Cd, Hg, and Zn. C. owstoni contained the highest concentrations of each of these elements. The concentrations of Cu, Pb, and Zn in each species were below the maximum levels permitted in food by the Australian Food Standards Code. The maximum permitted concentrations of As and Hg were exceeded in all species, and weekly consumption of 400 g of any of these sharks would result in intake of more than the FAO's provisional tolerable weekly intake. Although C. crepidator and D. calcea have strong relationships between length and mercury concentration, C. owstoni does not. Placing C. crepidator and C. owstoni in the same genus, therefore, is worth re-examination as the mechanisms for controlling mercury in C. owstoni appear to differ from that used by both C. crepidator and D. calcea.