Trace metal content in deep-water sharks from the eastern Mediterranean Sea

Trace metals were analyzed in the muscle and other organs from several species of deep-water sharks (particularly Centrophorus granulosus and Galeus melastomus) from 1280 to 1500 m depth in the eastern Mediterranean between 1985 and 1991. As has been shown with other pelagic fish, there was a significant correlation between specimen size and the mercury concentration in the muscle as well as in the liver and kidneys. For a given size, the level of mercury in sharks from the eastern Mediterranean was considerably higher compared with the same species caught off the west coast of Italy. There was no significant correlation between the concentrations of Cd, Cu, Zn and Fe in the muscle (or other organs) and body size. The overall trace metal content was considerably higher in the specimens from the eastern Mediterranean compared with the same species from the N. E. Atlantic. It is suggested that these higher-than-expected trace metal levels might be due to a relatively high trace metal content in the waters of the region or to the unusual physiology of these fish, possibly related to the extreme oligotrophic conditions in the area.