Radiocesium in Pacific Bluefin Tuna Thunnus orientalis in 2012 Validates New Tracer Technique

• Published in: Environmental science & technology 2013-03, Vol.47 (5), p.2287-2294
• Main Authors: Madigan, Daniel J, Baumann, Zofia, Snodgrass, Owyn E, Ergül, Halim A, Dewar, Heidi, Fisher, Nicholas S
• Format: Article
• Language: English
• Subjects: Animal Migration; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; California; Cesium Radioisotopes - analysis; Ecotoxicology, biological effects of pollution; Environmental Monitoring - methods; Fish migration; Food safety; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Japan; Marine and brackish environment; Marine Biology - methods; Methods and techniques (sampling, tagging, trapping, modelling...); Muscle Fibers, Fast-Twitch - chemistry; Nuclear accidents & safety; Pacific Ocean; Radiation; Radiometers; Tuna; Water Pollutants, Radioactive - analysis
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es4002423

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 134Cs signal, a radioisotope undetectable in Pacific biota prior to the Fukushima accident in 2011. We tested the efficacy of the radiocesium tracer by measuring 134Cs and 137Cs 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 134Cs (0.7 ± 0.2 Bq kg–1) and elevated 137Cs (2.0 ± 0.5 Bq kg–1) in their white muscle tissue. Most larger, older fish (n = 22) had no 134Cs and only background levels of 137Cs, showing that one year in the CCLME is sufficient for 134Cs and 137Cs 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 134Cs in all recent migrant PBFT supports the use of radiocesium as a tracer in migratory animals in 2012.