Researchers from the University of Tokyo's Atmosphere and Ocean Research Institute made the discovery at levels said to be well below the Japanese government’s provisional limit of 500 becquerels per kilogram for seafood.
They say that further studies are needed because the radioactive isotope is likely to have accumulated in fish that eat the plankton.
Meanwhile, the Environment Ministry announced that levels of cesium have soared to 154,000 becquerels per kilogram in soil around the Fukushima prefecture village of Iitate.
That’s about 25 miles to the northwest of the crippled reactors, and the highest level of contamination found so far.
Meltdowns at the Fukushima Daiichi nuclear power plant, which occurred in the wake of last March’s magnitude 9 earthquake and massive tsunami, have become the world’s greatest nuclear disaster since the Chernobyl disaster of 1986.
Photo: (Japan) Ministry of Science