Radioactive Bluefin Tuna Caught in San Diego Waters

In March 2011 a large magnitude-9 earthquake shook  in Japan waters sending a tsunami over the coast. The tsunami was so massive that it crippled Japan’s Fukushima Dai-ichi reactors, a nuclear power plant.

Since the events there have been results of nuclear fallout in the ocean, however, scientists have said the material should dilute over time.

Last year in August  Pacific Bluefin tuna were caught in the Pacific waters off the San Diego coast and all of them contained high levels of radioactive cesium.

“The levels of radioactive cesium were 10 times higher than the amount measured in tuna off the California coast in previous years. But even so, that’s still far below safe-to-eat limits set by the U.S. and Japanese government” (CBS News). 

 The fish caught shows they carried that contamination from Japan to the United States in a 6,000-mile swim. 

Nicholas Fisher, a professor at Stony Brook University in New York, who is also one of the scientists researching the findings, has commented on the subject. Yesterday, Fisher and other researchers published their study in the Proceedings of the National Academy of Science on the findings they found on the radiation contamination of the cesium.

In light of the ability of the huge fish being able to carry the radioactivity in that long of distance, Fisher has stated, “We were frankly kind of startled.” Nuclear fallout was not expected to stay in any of the large fish breeds that swim in the world’s oceans due to their high metabolism.

Despite the fact cesium has ‘biomagnification’ characteristics (radioactive levels increases from prey to predators when the material is digested), the scientists believe that the levels are not a danger to the public and will decrease. Fisher has written in an email that the levels of cesium will decrease close to 2 percent a day due to the fish’s high metabolism.

“Much will depend on the concentration in the prey fish, which in turn is ultimately dependent on the water concentration,” the professor stated. “If concentrations in water will eventually decline, as we would expect, due to dilution and dispersion, then concentrations in living organisms will eventually decline as well.”

Fisher says there will be further research to be conducted this year to see the current level of cesium in the Bluefin tuna. They also hope to track the levels in other species such as sharks, birds, and sea turtles that migrate the world’s ocean waters.

Photos courtesy of Steve Herman, Digital Globe, Alexandre Dulaunoy, and aes256 via WikiCommons and Flickr.