RADIOACTIVE CESIUM ACCUMULATION DURING DEVELOPMENTAL STAGES OF LARGEMOUTH BASS, MICROPTERUS SALMOIDES

Abstract

 It is considered that accumulation level of radioactive cesium in freshwater fish is higher than that in saltwater fish. However, accumulation pattern of radioactive cesium associated with growth is not fully clarified. To understand it, we measured levels of radioactive cesium and calculated cesium-137/ potassium 40 ratios in different developmental stages of largemouth bass, Micropterus salmoides. Radioactive cesium concentrations of the fish were decreased with hatching, and it increased in juvenile fish due to feeding. The levels of radioactive cesium became 8.6*10² times during six months after hatching. These suggest that change of radioactive cesium concentration during developmental stages of the freshwater fish is dependent on the start time of feeding and the feeding habitat.