Trace Levels of Fukushima Disaster Radionuclides in East Pacific Albacore

The Fukushima Daiichi power station released several radionuclides into the Pacific following the March 2011 earthquake and tsunami. A total of 26 Pacific albacore (Thunnus alalunga) caught off the Pacific Northwest U.S. coast between 2008 and 2012 were analyzed for 137Cs and Fukushima-attributed 134Cs. Both 2011 (2 of 2) and several 2012 (10 of 17) edible tissue samples exhibited increased activity concentrations of 137Cs (234–824 mBq/kg of wet weight) and 134Cs (18.2–356 mBq/kg of wet weight). The remaining 2012 samples and all pre-Fukushima (2008–2009) samples possessed lower 137Cs activity concentrations (103–272 mBq/kg of wet weight) with no detectable 134Cs activity. Age, as indicated by fork length, was a strong predictor for both the presence and concentration of 134Cs (p < 0.001). Notably, many migration-aged fish did not exhibit any 134Cs, suggesting that they had not recently migrated near Japan. None of the tested samples would represent a significant change in annual radiation dose if consumed by humans.