Bioaccumulation of 137Cs in pelagic food webs in the Norwegian and Barents Seas

Knowledge and documentation of the levels of radioactive contamination in fish stocks important to Norwegian fisheries is of major importance to Norwegian consumers and fish export industry. In the present study, the bioaccumulation of caesium-137 (137Cs) has been investigated in marine food webs in the Barents and Norwegian Seas. The contents of 137Cs in the different organisms were generally low (<1 Bq kg−1 wet weight), but a marked bioaccumulation was apparent: The concentration of 137Cs was about 10-fold higher in the harbour porpoise Phocoena phocoena, representing the upper level of the food web, than in the amphipod Themisto sp., representing the lower level of the food web. The Concentration Factors (CF=Bq kg−1 wet weight/Bq l−1 seawater) increased from 10±3 for a mixed sample of krill and amphipods to 165±5 for harbour porpoises.