Spatial distributions of and species differences in Sr accumulation in marine fishes from the Fukushima coastal region.

Large amounts of radionuclides were released into the ocean during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. One of the released radionuclides, Sr, tends to accumulate in bone, and could conceivably have long-term negative impacts on fishes. Here, we investigated Sr radioactivity concentrations in the vertebrae of demersal fishes collected off the coast of Fukushima Prefecture in January and July 2014. High Sr radioactivity concentrations were detected in fish collected from central Fukushima (offshore of the FDNPP) and southern Fukushima (offshore of Iwaki City), but were almost hardly detected in northern Fukushima (offshore of Soma City). Additionally, Sr radioactivity concentrations were higher among rays (Okamejei kenojei and Hemitrygon akajei: from 1.1 ± 0.5 to 103.3 ± 15.1 mBq/g Ca) and soles (Cynoglossus joyneri and Paraplagusia japonica: from 18.5 ± 2.8 to 52.8 ± 11.3 mBq/g Ca) than among other species. Vertebral stable Sr/Ca ratios also differed by fish species. Ca concentrations were relatively constant among species, but Sr concentrations were higher among elasmobranchs and soles, indicating that differences in Sr/Ca might be related to differences in Sr accumulation in fish vertebrae.