Impacts of the Fukushima Nuclear Accident on Fishery Products and Fishing Industry
On March 11, 2011, a massive earthquake and the resultant gigantic tsunami struck the Tohoku area of Japan (the Great East Japan Earthquake) and damaged many fishing boats and fishing ports. The earthquake and the subsequent tsunami also seriously caused the damage to Fukushima Daiichi Nuclear Power Plant (FNPP). Consequently, large amounts of radioactive cesium (Cs) were released into the atmosphere and ocean and subsequently polluted fishery products of Fukushima and adjacent prefectures. The Fukushima Prefectural Federation of Fisheries Cooperative Association (Fukushima FCA) has voluntarily stopped the fishing operations off Fukushima Prefecture since March 2011 due to the influence by the FNPP accident. The concentration of radioactive Cs in seawater rapidly decreased by ocean processes, and accordingly the concentration in fishery products did reduce. From April to June 2011, the proportion of inspected specimens off Fukushima exceeding the Japanese regulatory limit was 57.1%, but it decreased and continued to be 0% after April 2015. In addition, most of fishing industries in Fukushima Prefecture have been already restored from the damage by the earthquake and its aftermath. The Fukushima FCA started the trial fishing operation from June 2012.
KeywordsMonitoring research Fishery products Radioactive cesium Fukushima prefecture Trial fishing operation
On March 11, 2011, a massive earthquake (moment magnitude 9.0) and a resultant gigantic tsunami struck the Tohoku area of Japan (the Great East Japan Earthquake). According to the report by the Fisheries Agency of Japan (FAJ), the aftermath of the earthquake damaged around 29,000 fishing boats and 319 fishing ports, which were approximately 10% of each total number in Japan . Until January 2018, 18,614 fishing boats and all fishing ports have regained the function. The fishing industries in the tsunami-damaged areas excluding Fukushima Prefecture have been steadily recovering from the disaster. On the other side, the fishing industry in Fukushima has another unavoidable problem.
The earthquake and tsunami caused serious damage to FNPP. Consequentially, FNPP released a significant quantity of radionuclides into the atmosphere, and the fall out peaked around March 15, 2011 [2, 3, 4]. Although various radionuclides were released , the major radionuclides were radioactive iodine (I), 131I (physical half-life; 8.02 days), and two kinds of radioactive cesium (Cs), 134Cs (2.06 years) and 137Cs (30.1 years). Radioactivity of 134Cs and 137Cs released was approximately equal . The total quantity of 131I and 137Cs into the atmosphere between March 12, 2011, and May 1, 2011, was estimated to be approximately 200 PBq and 13 PBq, respectively . Furthermore, the amount of 137Cs deposited on the ocean surface from the atmosphere was estimated as 7.6 PBq  and 12–15 PBq , and meaning that most of 137Cs released to the atmosphere was introduced into the ocean. In addition, extremely contaminated cooling water, which interacted with the ruptured nuclear fuel rods, was leaked from a cracked sidewall near the intake channel of Unit 2 reactor during April 1–6 in 2011. Nuclear Emergency Response Headquarters of Japan (NERH) estimated that the contaminated water contained 4.7 PBq of radionuclides including 131I, 134Cs, and 137Cs . Another report indicated that the direct release to the ocean had already been going on March 26, 2011, and estimated that the total amount of 137Cs directly released was 3.5 ± 0.7 PBq from March 26, 2011 to the end of May 2011 .
The Fukushima FCA did not fully grasp the radioactive pollution of fishery products off Fukushima by the large amounts of radionuclides from FNPP in March 2011. Additionally, not all fishing boats and fishing ports in Fukushima Prefecture were damaged by the aftermath of the earthquake. However, the Fukushima FCA decided to voluntarily stop the fishing operations off Fukushima for the food safety on March 15, 2011 . Consequently, this voluntary stop of the fishing operations has been continuing from March 2011 to the present (August, 2019), by the monthly update. In such a situation, the Fukushima FCA started the trial fishing operation from June 2012 off Fukushima .
In this chapter, we introduce the radioactive pollution in fishery products and the state of the fisheries industry in Fukushima Prefecture.
3.2 Radioactive Pollution of Fishery Products
The change of main year-class composing a population was a cause for decrease of radioactive Cs concentrations in fishery products including demersal fishes. A year-class-related differences of radioactive Cs concentration in some fish species, Pacific cod (Gadus microcephalus) and Japanese flounder (Paralichthys olivaceus), have been reported [28, 29]. The 2010 year-class and older classes had relatively higher concentrations of radioactive Cs than 2011 year-class and younger classes. The finding that year-classes born after the FNPP accident had lower concentration indicates that they incorporated only a small amount of radioactive Cs from the benthic food web.
High radioactive Cs concentration, 25,800 Bq/kg-wet, was detected in the specimen prepared from two greenlings (Hexagrammos otakii). The fish samples were caught close to Ota River approximately 20 km from FNPP in August 2012. Although these two outlier samples were thought to have migrated from the FNNP port, the probability of such outlier samples being found off Fukushima was exceedingly low . Indeed, some fishes caught within the FNPP port remained highly contaminated, and the maximum concentration, 720,000 Bq/kg-wet, was detected in greenling collected on February 21, 2013. Therefore, TEPCO has set nets and prevented fishes from leaving the port. They also caught fishes in the FNPP port using fishing nets, and the total number of fishes was about 5000 samples from 2012 to 2018 [16, 30, 31, 32].
3.3 Monitoring Research in Fishery Products
Number of exceeding the Japanese regulatory limit in the inspection for distribution foods
Meats (including wild animals)
Radioactive strontium (89Sr and 90Sr) is one of the nuclear fission products as well as 137Cs. Therefore, many people have been concerned about pollution of fishery products by radioactive Sr since the FNPP accident happened. Strontium-90 had been detected in fishery products before the FNPP accident . The main source of 90Sr in the North Pacific Ocean off Japan was the global and close-in radioactive fallout after the atmospheric nuclear bomb tests and the Chernobyl NPP accident [38, 39]. The average concentration of 90Sr in marine fishes of the North Pacific Ocean off Japan was 0.025 ± 0.021 Bq/kg-wet in the past two decades before the FNPP accident .
Owing to the lower volatility than Cs, the amount of 90Sr released into the atmosphere from the FNPP accident is estimated to be about 0.14 PBq , which is two orders of magnitude smaller than that of radioactive 137Cs, 20 PBq [6, 7]. An extremely contaminated cooling water was leaked from a cracked sidewall near the intake channel of Unit 2 from late March to early April 2011 [8, 9]. The contaminated water including high concentration of radioactive Sr and Cs directly flowed into the ocean. Based on the initial 137Cs/90Sr activity ratio released from the FNPP accident and 3.5 PBq of 137Cs directly was released into the ocean, the amount of 90Sr in the contaminated water was estimated to be approximately 0.04 PBq [9, 41]. The International Atomic Energy Agency (IAEA) summarized the concentration factor of many elements for various aquatic organisms . The value of concentration factor for Sr in marine fishes was 3 and lower than that for Cs, 100. In addition, 90Sr in seawater was immediately diluted to the background level . Therefore, 90Sr concentration in fishery products was notably lower than that of 137Cs even off Fukushima, and 90Sr derived from the FNPP accident would not be detected in fishery products caught outside off Fukushima . In conclusion, the influence of the FNPP accident by 90Sr pollution on fishery products has been limited to the area off Fukushima though negligible [40, 43].
3.4 Trial Fishing Operations in Fukushima
The fishery products off Fukushima were polluted by large amounts of radioactive Cs released from FNPP. However, the Japanese and the Fukushima prefectural governments did not revoke the fishing licenses in Fukushima Prefecture, because the Fukushima FCA voluntarily continued to stop the fishing operations off Fukushima for the food safety from March 15, 2011 by the monthly update. In February 2012, the Fukushima FCA established the Fukushima Prefectural Fisheries Reconstruction Committee (Fukushima FRC) with external experts in order to reconstruct the fishery industry and restart the fishing operation off Fukushima .
Amount of landing in the trial fishing operations in Fukushima Prefecture and comparison with that before the FNPP accident
Amount of landing (t)
Comparison with 2010 (%)
We appreciate the staff members of the Fukushima FCA for providing the amount of landing data in the trial fishing operation. We thank all fishery workers in Fukushima Prefecture for cooperating with the monitoring research. We also thank the staff members of Radioecology Group for great help.
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