Kaoru Nakata · Hiroya Sugisaki Editors Impacts of the Fukushima Nuclear Accident on Fish and Fishing Grounds Impacts of the Fukushima Nuclear Accident on Fish and Fishing Grounds Kaoru Nakata • Hiroya Sugisaki Editors Impacts of the Fukushima Nuclear Accident on Fish and Fishing Grounds Editors Kaoru Nakata Hiroya Sugisaki Research Management Department National Research Institute of Fisheries Fisheries Research Agency Sciences Yokohama , Kanagawa , Japan Fisheries Research Agency Yokohama , Kanagawa , Japan ISBN 978-4-431-55536-0 ISBN 978-4-431-55537-7 (eBook) DOI 10.1007/978-4-431-55537-7 Library of Congress Control Number: 2015939907 Springer Tokyo Heidelberg New York Dordrecht London © The Editor(s) (if applicable) and The Author(s) 2015 . This book is published with open access at SpringerLink.com Open Access This book is distributed under the terms of the Creative Commons Attribution Noncom- mercial License, which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. All commercial rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifi cally the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfi lms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper Springer Japan KK is part of Springer Science+Business Media ( www.springer.com ) Foreword On March 11, 2011, the most disastrous earthquake and tsunami in modern Japanese history occurred in northeast Japan. They caused a great calamity for the people and industries on the Pacifi c coast of the Tohoku region of Japan, one of the most important regions for Japanese fi sheries. The Fukushima Dai-ichi Nuclear Power Plant (FNPP) was covered by a 15-m-high tsunami, and the electric power supply to its four nuclear reactors was severed, resulting in hydrogen explosions and the melt- down of the core. This accident caused the elevation of the level of anthropogenic radioactivity in the marine environment in the western North Pacifi c from atmo- spheric fallout and direct discharges of highly radioactive waters. Security of food safety of marine products is a great concern for the people in the world and espe- cially for the people involved in the fi sheries industry. The Fisheries Research Agency (FRA) has been conducting research and monitoring the radioactivity of fi sh and shellfi sh since the 1950s, when we were worried about the effect of nuclear arms tests in the ocean to marine environments and products. Because the FRA has enough experience and knowledge of research on the radioactivity of large quantities of specimens, we accepted the requests from the national government to analyze the radioactivity of marine products fi shed all over Japan and started to make a plan to monitor radioactivity of various marine products fi shed around Japan in coop- eration with local governmental institutes just after the accident. This book describes the results of the research on the effect of radioactivity to ocean and coastal ecosystems and various marine and freshwater fi sh caused by the FNPP accident of the huge magnitude of radioactivity on the ecosystems around Japan. This is the fi rst report on the effect on the hydrosphere ecosystem from the point of view of marine ecology and fi sheries oceanography. A scientifi cally precise description of the distribution and variation of radioactive elements in the ecosystem is presented in detail in this publication. Of course, this is the fi rst step in revealing v vi Foreword the anthropological effect of radioactivity on the ecosystem, and we should con- tinue the research. I trust that this book will contribute to overcoming the tragedy and enhance the culture of human beings in the world. President of the Fisheries Research Agency Masanori Miyahara Yokohama , Japan Pref ace On March 11, 2011, the Great East Japan Earthquake occurred. The earthquake itself and the resulting tsunami caused the Fukushima Daiichi Nuclear Power Plant (FNPP) accident. As a result, a large volume of radionuclides was released into the environment as fallout, which contaminated both freshwater and marine systems. On April 2, heavily contaminated water was released around the No. 2 reactor into the ocean. Several further leakages of water contaminated with radionuclides, as well as a release of low-level contaminated water by the Tokyo Electric Power Company (TEPCO), occurred around FNPP up until May 2011. This was the fi rst time that heavily contaminated water originating from a nuclear power plant acci- dent had been directly released into the ocean over a relatively short period. Since then, contaminated fi sh with relatively high radiocesium concentrations (higher than ca. 100 Bq/kg-wet) have often been caught in the coastal areas of Fukushima and in adjacent prefectures. The Fisheries Research Agency (FRA) has monitored radioactive substances in marine organisms around Japan since 1954, when the H-bomb test was carried out on Bikini Atoll. Soon after the FNPP accident, the FRA began monitoring radionu- clides in fi sheries resources and their habitats. Decreasing trends of radiocesium concentration in small pelagic fi sh and demersal fi sh have been obvious since sum- mer 2011 and winter 2012, respectively, based on intensive monitoring of radioac- tivity in fi sheries products by local governments and the FRA ( http://www.jfa.maff. go.jp/j/housyanou/kekka.html ). However, incidents that have worried the general public, including fi shermen, have often occurred, including catches of cod with relatively high radiocesium con- centrations in areas distant from Fukushima Prefecture, a catch of extremely highly contaminated fat greenlings, and continuing contamination of fi sh in some freshwa- ter systems. Various questions have therefore been raised by the public, such as: When will the radiocesium concentrations of fi sh and fi shing grounds recover to the level before the accident? Will the radiocesium in fi sh continue to be accumulated in fi sh via the food chain, like heavy metals and some kinds of chemicals? What is vii viii Preface the mechanism for the occurrence of extremely highly contaminated fi sh? Is the contamination of fi sh with radiocesium an ongoing phenomenon? In order to restore trust in fi sheries products from the Tohoku district, both abroad and among the Japanese people, it is important to answer these questions based on scientifi c data. Accordingly, the FRA has conducted research to clarify the impacts of the FNPP accident on fi sh and fi shing grounds, and the dynamics of radionu- clides through both marine and freshwater systems by in situ investigation, rearing experiments, and the use of simulation models. Although our research is ongoing, the main body of our investigations was con- ducted from 2011 to 2013. Yokohama, Japan Tokio Wada Kaoru Nakata Hiroya Sugisaki Contents 1 Introduction: Overview of Our Research on Impacts of the Fukushima Dai-ichi Nuclear Power Plant Accident on Fish and Fishing Grounds ................................................. 1 Kaoru Nakata and Hiroya Sugisaki Part I Seawater and Plankton 2 134Cs and 137Cs in the Seawater Around Japan and in the North Pacific .............................................................. 11 Hideki Kaeriyama 3 Temporal Changes in 137Cs Concentration in Zooplankton and Seawater off the Joban–Sanriku Coast, and in Sendai Bay, After the Fukushima Dai-ichi Nuclear Accident .......................... 33 Hideki Kaeriyama Part II Sediments and Benthos 4 Three-Dimensional Distribution of Radiocesium in Sea Sediment Derived from the Fukushima Dai-ichi Nuclear Power Plant ............................................................................... 53 Daisuke Ambe , Hideki Kaeriyama , Yuya Shigenobu , Ken Fujimoto , Tsuneo Ono , Hideki Sawada , Hajime Saito , Mikiko Tanaka , Shizuho Miki , Takashi Setou , Takami Morita , and Tomowo Watanabe 5 Radiocesium Concentrations in the Organic Fraction of Sea Sediments ...................................................................... 67 Tsuneo Ono , Daisuke Ambe , Hideki Kaeriyama , Yuya Shigenobu , Ken Fujimoto , Kiyoshi Sogame , Nobuya Nishiura , Takashi Fujikawa , Takami Morita , and Tomowo Watanabe ix x Contents 6 Bottom Turbidity, Boundary Layer Dynamics, and Associated Transport of Suspended Particulate Materials off the Fukushima Coast ....................................................... 77 Hiroshi Yagi , Kouichi Sugimatsu , Shigeru Kawamata , Akiyoshi Nakayama , and Toru Udagawa 7 Investigation of Radiocesium Translation from Contaminated Sediment to Benthic Organisms .......................... 91 Yuya Shigenobu , Daisuke Ambe , Hideki Kaeriyama , Tadahiro