The massive earthquake and subsequent tsunami that hit Japan in March 2011 killed thousands of people, destroyed many coastal villages and caused a meltdown at the Fukushima nuclear power station. When the reactors overheated, radionuclides were released into the atmosphere and surrounding land and water. This contaminated farm animals like cattle and local seafood. A recently published study “Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California” by Drs. Madigana, Baumannb and Fisher found that radioactive contamination has crossed the Pacific Ocean. Pacific Bluefin Tunas are a large, pelagic fish, growing over 900 lbs, which spawn in and around Japan. Some young Pacific Bluefin Tuna then swim or migrate across the Pacific Ocean to feed in waters off the US west coast, and swim back again after a few years to spawn. The study mentioned above found that Pacific Bluefin Tuna migrating from Japanese waters after the nuclear meltdown occurred had unnaturally high levels of radioactive cesium isotopes when they were caught in Californian waters. Although contaminated, the level of radioactivity in the tuna is considered to be well within safe limits and thus does not pose a threat to people who eat it. It does highlight, however, that the seafood we eat often originates from distant shores where they are exposed to local events.
The full study can be found at: http://www.pnas.org/content/early/2012/05/22/1204859109.full.pdf+html?sid=6c35039b-0836-428c-8b97-4527c6bfd3f5
By Dr Alan Duckworth