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Survey Report for Fish and Seashells of the Sea Within a 20 Km Radius Of

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Survey Report for Fish and Seashells of the Sea Within a 20 Km Radius Of Survey report* for fish and seashells of the sea within a 20 km radius of Fukushima Daiichi Nuclear Power Station (Samples taken during the period between July and September, 2014) December 5, 2014 Tokyo Electric Power Company * Except for the survey data obtained inside the port of Fukushima Daiichi Nuclear Power Station. 1. Objectives for surveying fish and seashells of the sea within a 20 km radius of Fukushima Daiichi NPS (1) Grasp radioactive cesium levels of each fish species. ・Comparison with the food product standards (the total of cesium: 100 Bq/ kg) (2) Grasp the areal distribution of radioactive cesium levels in fish and seashells. ・Sampling at fixed surveying spots (gillnet and trawler fisheries) (3) Grasp the transition with time of radioactive cesium levels of fish and seashells. ・Basic data taken for the transition prediction. 1 2‐1. Survey results (radioactive cesium levels by fish species) More than 99% of the samples taken indicate that the measured levels fall below the standard value. Standard value: a total of 100 radioactive cesium (Bq/kg) Samples taken during Jul. to Sep. 2014. Samples taken during Apr. to Jun. 2014. [Top 3 species with high levels] [Top 3 species with high levels] （Unit: Bq/kg） （Unit: Bq/kg） 38 1) Common skete 131 42 1) Common skete 370 2) Stone flounder 96 2) Sebastes chen 199 No. of species (of which, 1 case （of which, 4 cases 3) Microstomus achne 91 3) Microstomus achne 176 exceeded the exceeded the standard value) standard value) [Below the detection limit value] [Below the detection limit value] 1) Zenopsis nebulosa, 1) crimson sea bream 2) Yellow goosefish, 2) White croaker 3) Japanese amberjack, 3) Banded houndshark No. of 4) jack mackerel, 4) Dasyatis matsubarai measurements 275 307 5) chub mackerel, and others. 5) Dwarf squid taken (of which, 1 case (of which, 10 cases exceeded the exceeded the 6) jack mackerel (total) standard value) standard value) 7) Conger‐eel, and others (Note) Parts measured: Muscle for fish (except for Yellow goosefish) and octopus‐kind. A whole body for yellow goosefish, squids and crabs. Species with a tendency to exceed the standard value: Common skete Species with a tendency to fall below the standard value: Flatfish, Marbled sole, Greenling, and Zeus faber, etc. 2 2‐2. Survey results (areal distribution of cesium) The ratio of exceeding the standard value is showing a decreasing tendency. The same tendency is also found with the surveying spots for gillnet and trawl‐net in the coastal area. Samples taken during Jul. to Sep. 2014. Samples taken during Apr. to Jun. 2014 No. of No. of No. of results exceeding No. of results exceeding measurements Ratio (%) measurements Ratio (%) the standard value the standard value taken taken T‐B１ 25 0 0 27 1 4 Gillnet T‐B2 39 0 0 37 0 0 T‐B3 23 0 0 36 0 0 T‐B4 28 0 0 33 0 0 T‐S1 24 0 0 28 0 0 T‐S2 18 0 0 19 0 0 Trawl T‐S3 29 0 0 25 0 0 ‐ net T‐S4 30 0 0 32 1 3 T‐S5 22 0 0 22 2 9 T‐S7 19 1 5 20 5 25 T‐S8 18 0 0 28 1 4 3 2‐3. Survey results (transition with time of radioactive cesium levels) [Tendency found for the area within a 20km radius of Fukushima Daiichi NPS] The data obtained from the measurement of fish and shellfishes within a 20 km radius of Fukushima Daiichi NPS was all in all within the range of the measurement results obtained outside a 20 km radius by Fukushima prefecture etc. , showing a decreasing tendency. [Tendency of radioactive cesium levels] • Fish species with a decreasing tendency over time: flatfish, greenling, and others. • Fish species exceeding the standard value: common skete only Note 1: Further data is required to be collected for fish and seashells within a 20 km radius of Fukushima Daiichi NPS. Note 2: As for the transition with time, it is assumed that their respective living characteristic such as feed type, living environments (seawater and marine sediment, etc) and the way of traveling may have affected to the transition, for which further study is necessary on the mechanism. 4 [Reference] Transition with time of cesium levels of flatfish and greenling Figure図1．ヒラメの測定結果（Cs134+137） 1. Measurement results of flatfish (Cs134+137) 図２．アイナメの測定結果（Cs134+137）Figure 2. Measurement results of greenling (Cs134+137) 100000 100000 o/s 20 km 福島１F２０ o/s 20 km of 1F 福島１F２０ ｋｍ圏外 of 1F ｋｍ圏外 10000 w/in福島１F２０ 20 10000 km of 1F w/in福島１F２０ 20 km ｋｍ圏内 of 1F ｋｍ圏内 ) （生 ）） 1000 ｇ (Bq/kg) 1000 /ｋ (Bq/kg ｑ levels levels 100 100 Radiation Radiation 放射能濃度（B 放射能濃度（Bｑ/ｋｇ（生）） 10 10 1 1 JunH23.6.6 6, 2011 Dec H23.12.23 23, 2011 Jul H24.7.1010, 2012 Jan H25.1.26 26, 2013 Aug H25.8.14 14, 2013 Mar H26.3.2 2, 2014 Sep H26.9.18 18, 2014 JunH23.6.6 6, 2011 Dec H23.12.23 23, 2011 Jul H24.7.10 10, 2012 Jan H25.1.26 26, 2013 Aug H25.8.14 14, 2013 Mar H26.3.2 2, 2014 Sep H26.9.18 18, 2014 Data release公表日 date Data release公表日 date (Note) Measurement results for the area outside a 20 km radius of Fukushima Daiichi NPS were obtained from the website of the Fishery Agency and are converted into graph. Of note, the data remained below the detection limit value is not plotted. 5 2‐4. Survey results for nuclides other than cesium Unit: Bq/kg Nuclide Samples taken during Jul. to Sep. 2014 Samples taken during Apr. to Jun. 2014 (Half‐lives) No. of samples Result No. of samples Result Max.: N/A Max.: N/A Ag‐110m 0 Min.: N/A 0 Min.: N/A (Approx. 250 days) Ave.: N/A Ave.: N/A *1 5 5 Max.: 0.59 Max.: 1.4 Common skete: 2 Strontium 90 Common skete: 3 Min.: 0.065 Schlegel’s black rockfish: 1 Min.: 0.039 Stone flounder: 1 (Approx. 29 yrs) Sebastes cheni: 1 Microstomus achene: 1 Ave.: 0.37 Ave.: 0.50 Microstomus achene: 1 No detection found for Ag‐100m. Strontium 90 levels were quite low at 1/100 to 1/1000 compared with that of Cesium 137. *1: Top five fish samples with high cesium levels detected during the specified period for the sampling were selected and measured after ashing them. (Note: Top two fish samples were listed until the first quarter of FY2013) 6 3. Survey plan Survey for the following three items continue to be Gillnet survey location (7 spots) conducted to grasp: Trawl‐net survey location (4 spots) (1) A tendency of radioactive cesium levels by fish species, (2) Areal distribution of radioactive cesium levels of fish and seashell , and (3) Transition with time of radioactive cesium levels of fish and seashells. 1 F 2 F For the time being, these sampling/ measurement activities are conducted on a monthly basis at the eleven sampling spots. (sampling may be ceased due to weather conditions.) Figure 3. Survey locations for fish and seashells (Mar. 2014) 7.
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