1 Introduction: Overview of Our Research on Impacts of the Fukushima Dai-ichi Nuclear Power Plant Accident on Fish and Fishing Grounds -- Part I Seawater and Plankton -- 2 134Cs and 137Cs in the Seawater Around Japan and in the North Pacific -- 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 -- Part II Sediments and Benthos -- 4 Three-Dimensional Distribution of Radiocesium in Sea Sediment Derived from the Fukushima Dai-ichi Nuclear Power Plant -- 5 Radiocesium Concentrations in the Organic Fraction of Sea Sediments -- 6 Bottom Turbidity, Boundary Layer Dynamics, and Associated Transport of Suspended Particulate Materials off the Fukushima Coast -- 7 Investigation of Radiocesium Translation from Contaminated Sediment to Benthic Organisms -- Part III Marine Fish -- 8 Detection of 131I, 134Cs, and 137Cs Released into the Atmosphere from FNPP in Small Epipelagic Fishes, Japanese Sardine and Japanese Anchovy, off the Kanto Area, Japan -- 9 Radiocesium Concentration of Small Epipelagic Fishes (Sardine and Japanese Anchovy) off the Kashima-Boso Area -- 10 Why Do the Radionuclide Concentrations of Pacific Cod Depend on the Body Size? -- 11 Radiocesium Contamination Histories of Japanese Flounder (Paralichthys olivaceus) After the 2011 Fukushima Nuclear Power Plant Accident -- Part IV Mechanisms of Severe Contamination in Fish -- 12 Evaluating the Probability of Catching Fat Greenlings (Hexagrammos otakii) Highly Contaminated with Radiocesium off the Coast of Fukushima -- 13 Analysis of the Contamination Process of the Extremely Contaminated Fat Greenling by Fukushima-Derived Radioactive Material -- 14 Contamination Levels of Radioactive Cesium in Fat Greenling Caught at the Main Port of the Fukushima Dai-ichi Nuclear Power Plant -- Part V Freshwater Systems -- 15 Comparison of Radioactive Cesium Contamination of Lake Water, Bottom Sediment, Plankton, and Freshwater Fish Among Lakes of Fukushima Prefecture, Japan, After the Fukushima Fallout -- 16 Radiocesium Concentrations and Body Size of Freshwater Fish in Lake Hayama 1 Year After the Fukushima Dai-Ichi Nuclear Power Plant Accident -- 17 Spatiotemporal Monitoring of 134Cs and 137Cs in Ayu, Plecoglossus altivelis, a Microalgae-Grazing Fish, and in Their Freshwater Habitats in Fukushima -- 18 Radiocesium Concentrations in the Muscle and Eggs of Salmonids from Lake Chuzenji, Japan, After the Fukushima Fallout -- 19 Assessment of Radiocesium Accumulation by Hatchery-Reared Salmonids After the Fukushima Nuclear Accident.