New Japan Import: Radioactive Bluefin Study finds tuna off California with cesium levels 10X higher than usual By Polly Davis Doig, Newser Staff Posted May 29, 2012 7:37 AM CDT 5 comments Comments In this March 5, 2007 file photo bluefin tuna swim. Radioactive bluefin tuna have made their way across the Pacific from Japan. (AP Photo/Chris Park) (Newser) – Radiation from Japan's nuclear meltdown keeps hitting US shores: The latest comes in the form of the bluefin tuna, a massive fish that can top 1,000 pounds and which spawn off the coast of Japan and rocket 6,000 miles across the Pacific to school off of California and Baja California. Bluefins arriving on the West Coast five months after the Fukushima disaster showed much higher levels of cesium-134 and cesium-137 than previous specimens. "We were frankly kind of startled," one of the researchers tells the AP. Underscoring that surprise is the time and distance involved since the bluefins were first exposed to the radiation—in which scientists expected they would have metabolized and shed much of the cesium. "That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing," says the expert. The bad-good news: Though the bluefins' cesium levels were more than 10 times higher than normal, they are still considered safe to eat under both US and Japanese regulations. Scientists plan a more comprehensive study this summer.