• Marine fish have the ability to quickly discharge cesium and the other minerals from their bodies. When the concentration of radioactive cesium in seawater decreases, the concentrations in marine fish also decrease.
• The tendency of decrease in concentration of radioactive cesium in demersal fish is similar to that in marine sediment. This means that the radioactive cesium in demersal fish is possibly affected by marine sediment.。

Fig.1　Results for inspection of radioactive materials in marine species in Fukushima Prefecture（Number of samples exceeding 100 Bq/kg and its ratio in every three months)

Reference： Report on Inspection of Radioactive Materials in Marine Products (January 12, 2021) (Fisheries Agency)

Fig.2　Time dependencies of radioactive cesium concentration in marine sediment and demersal fish

Reference：
Upper figure: S. Otosaka, ISOTOPE NEWS 710, 12-15 (2013)., S. Otosaka, and T. Kobayashi, Environ Monit Assess 185, 5419–5433 (2013), DOI 10.1007/s10661-012-2956-7
Lower figure: Data are extracted from Report on Inspection of Radioactive Materials in Marine Products (October 16, 2015) (Fisheries Agency).

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Reference

1. 水産庁(2024): 水産物の放射性物質調査の結果について. https://www.jfa.maff.go.jp/j/housyanou/kekka.html（2024.11.18アクセス）”
2. 乙坂重嘉(2013): 海底堆積物中の放射性セシウム濃度の推移, ISOTOPE NEWS, No.710, 12-15.
3. Otosaka, S. and Kobayashi, T. (2013): Sedimentation and remobilization of radiocesium in the coastal area of Ibaraki, 70 km south of the Fukushima Dai-ichi Nuclear Power Plant, Environmental Monitoring Assessment, vol. 185, no. 7, 5419–5433.https://doi.org/10.1007/s10661-012-2956-7