title: Radiocesium in Pacific bluefin tuna Thunnus orientalis in 2012 validates new tracer technique.
abstract: The detection of Fukushima-derived radionuclides in Pacific bluefin tuna (PBFT) that crossed the Pacific Ocean to the California Current Large Marine Ecosystem (CCLME) in 2011 presented the potential to use radiocesium as a tracer in highly migratory species. This tracer requires that all western Pacific Ocean emigrants acquire the (134)Cs signal, a radioisotope undetectable in Pacific biota prior to the Fukushima accident in 2011. We tested the efficacy of the radiocesium tracer by measuring (134)Cs and (137)Cs in PBFT (n = 50) caught in the CCLME in 2012, more than a year after the Fukushima accident. All small PBFT (n = 28; recent migrants from Japan) had (134)Cs (0.7 ± 0.2 Bq kg(-1)) and elevated (137)Cs (2.0 ± 0.5 Bq kg(-1)) in their white muscle tissue. Most larger, older fish (n = 22) had no (134)Cs and only background levels of (137)Cs, showing that one year in the CCLME is sufficient for (134)Cs and (137)Cs values in PBFT to reach pre-Fukushima levels. Radiocesium concentrations in 2012 PBFT were less than half those from 2011 and well below safety guidelines for public health. Detection of (134)Cs in all recent migrant PBFT supports the use of radiocesium as a tracer in migratory animals in 2012.
authors: Hopkins Marine Station, Stanford University , 120 Ocean View Boulevard, Pacific Grove, California 93950, United States.
authors: Daniel J
authors: DJ
authors: Madigan
authors: Zofia
authors: Z
authors: Baumann
authors: Owyn E
authors: OE
authors: Snodgrass
authors: Halim A
authors: HA
authors: Ergül
authors: Heidi
authors: H
authors: Dewar
authors: Nicholas S
authors: NS
authors: Fisher
mesh_terms: D025041:Animal Migration; D000818:Animals; D002140:California; D002588:Cesium Radioisotopes / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D007564:Japan; D008386:Marine Biology / Q000379:methods*; D018656:Muscle Fibers, Fast-Twitch / Q000737:chemistry; D010140:Pacific Ocean; D014413:Tuna; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive