Radiocesium concentrations and body size of freshwater fish in Lake Hayama 1 year after the Fukushima Dai-Ichi nuclear power plant accident

Abstract

We measured radiocesium ( 134 Cs + 137 Cs) concentrations in five freshwater fish species in Lake Hayama, Fukushima Prefecture, 1 year after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident in March 2011. The five species included bluegill (Lepomis macrochirus), Carassius spp. (Carassius auratus langsdorfii and Carassius cuvieri), Japanese dace (Tribolodon hakonensis), largemouth bass (Micropterus salmoides), and smallmouth bass (Micropterus dolomieu). We observed a “positive size effect” for radiocesium concentrations in fish muscle, but the coefficient of determination was low for bluegill, Carassius spp., and Japanese dace. In contrast, the coefficient of determination was high for the exponential relationship between body size and radiocesium concentrations in largemouth and smallmouth bass. The geometric mean radiocesium concentration in each body size class was generally higher for carnivorous fish than for omnivorous and herbivorous fish.