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

Deep sea dog sharks (Deania calcea, Centroscymnus crepidater, and Centroscy mnus owstonii) were captured from the waters off western Victoria, Australi a, in April and May 1998. The elements As, Ca, Cd, Cu, Fe, Hg; K, Mg, Mn, N a, Sr, and Zn were detdcted in the muscle tissue. The concentrations of Al, Ba, Be, Cr, Mo, Ni, Pb, and V were below the detection limits of the instr umental techniques employed (ICP-ES and GF-AAS). However, significant conce ntration 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 maximu m permitted concentrations of As and Hg were exceeded in all species, and w eekly 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. crepi dator and D. calcea have strong relationships between length and mercury co ncentration, C. owtstoni does not. Placing C. crepidator and C. owstoni in the same genus, therefore, is worth re-examination as the mechanisms for co ntrolling mercury in C. owstoni appear to differ from that used by both C. crepidator and D. calcea.