Concentrations of mercury (Hg) and cadmium (Cd), and the condition of some coastal Baltic fishes

Of eight main selected coastal fish species; Baltic sprat, herring, smelt, eelpout, four-horn sculpin, perch, flounder and turbot, five; herring, smelt, eelpout, four-horn sculpin, flounder, seem most suitable for heavy metal monitoring in coastal waters in the Norhern Baltic Sea. In general low concentrations of Hg and Cd were measured from the edible parts (muscle tissue) of the fishes. Predatory species, as bull-rout, pike, perch, turbot, however were significantly more contaminated than non-predatory fishes. In a few cases the concentrations of Hg in muscle tissue of the investigated predatory fishes exceeded the stipulated safety levels for fish as food for human consumption. The concentrations of Hg were higher in inshore fishes compared to open-sea fishes. The concentrations of Cd were elevated in eelpouts from the Finnish Archipelago Sea, and the Gulf of Finland compared to eelpouts from the Gulf of Riga, and the Firth of Kiel. The same distinction also was valid for flounder from the waters around the Åland Islands, and the Gulf of Finland, compared to flounder from the Firth of Kiel.