Accumulation of certain long-lived radionuclides by fish

In addition to the monitoring programmes at open sea and around the nuclear power plants, special studies were designed in order to improve the information on factors influencing the accumulation of 90Sr and 137Cs by fish. Baltic herring and pike were chosen for the fish species to be studied. In sea water, the annual mean concentrations of 90Sr were lowest in the Gulf of Bothnia and highest in the Gulf of Finland, whereas the 137Cs concentrations were lowest in the inner part of the gulfs. The concentrations of both nuclides in fish and the CF values were in general higher in the inner parts of the gulfs, especially in the northernmost end of the Gulf of Bothnia. In the entire material, the CF values of 90Sr were 3-7 for Baltic herring and 1-2 for pike and those of 137Cs 150-300 for Baltic herring and 300-650 for pike