Occurrence of methyl mercury in pike and Baltic herring from the Turku archipelago

Abstract

The content of methyl mercury in pike and Baltic herring from seven different areas of the Turku archipelago (the southwestern coast of Finland) was studied. Pike muscle contained on average 0·27 mg Hg/kg on a fresh tissue basis. However, the concentrations of methyl mercury varied considerably between individuals from the same fish population, e.g. from 0·06 to 1·3 mg/kg, depending on the weight (and age) of fish. The values for methyl mercury in standardised weight (1 kg) pikes were on a natural level (varying between 0·19 to 0·25 mg/kg) in all other areas of the archipelago, except in the area near the city of Turku, where slight contamination (0·39 mg/kg) was noticed. In different tissues of pike the level of methyl mercury decreased in the following order: muscle tissue > liver ≥ kidney ⪢ gonads. Baltic herring muscle contained on average 0·09 mg Hg/kg, the value being only one-third of that of pike muscle.