This publication shares the experience gained in the Fukushima Prefecture on environmental transfer data from Japan after the release of radionuclides to the environment from the Fukushima Daiichi NPP (FDNPP). It provides a compilation and analyses of the radioecological information obtained during the cooperation between the IAEA and Fukushima Prefecture between 2012 and 2022. In particular, it examines the behaviour of radiocaesium in freshwater ecosystems and the effectiveness of decontamination and remediation, providing a comparison with global experience. This information is useful for informing the management of areas affected by enhanced levels of radiocaesium after an accidental release from a nuclear facility.