Mercury, cadmium and lead in black scabbardfish (Aphanopus carbo Lowe, 1839) from mainland Portugal and the Azores and Madeira archipelagos

Total mercury (THg), cadmium (Cd) and lead (Pb) concentrations were investigated in muscle, liver and gonad tissue of black scabbardfish (Aphanopus carbo) from the southern northeast Atlantic at three Portuguese locations: the mainland and the archipelagos of the Azores and Madeira. Particular emphasis was placed on the comparison of metal levels between geographic locations. Other factors such as size, sex and sexual maturity were also investigated. The median concentrations (mg/kg ww) of THg showed a decreasing trend in the order liver>muscle>gonad. Cadmium levels decreased in the order liver>gonad>muscle and Pb levels decreased in the order gonad>liver>muscle. According to the EU limits, the concentration observed in some specimens, particularly those of THg, raises some food safety concerns. In all the tissues the concentrations of each toxic metal differed between locations. In particular: i) THg concentrations in specimens from Madeira were significantly higher than those from the Azores and the mainland; ii) Cd levels in specimens from the mainland were significantly higher than those from Madeira and the Azores; and iii) for all analysed tissues Pb levels were significantly higher in specimens from the Azores than in those from the mainland. The differences in toxic metal levels between locations were further discussed in relation to aspects of species dynamics and the influence of the main environmental features at each location.