Some fish species in offshore Fukushima, Japan have the ability to accumulate a specific nuclide (radioisotope)

1 Coimbatore Institute of Technology (CIT), Coimbatore, Tamil Nadu 641014, India. 2 Department of Ocean Sciences, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Konan 4-Chome, Minato-Ku, Tokyo 108-8477, Japan. 3 Institute of Product Design and Manufacturing (IPROM), Universiti Kuala Lumpur (Uni.KL), 119 Jalan 7/91, Taman Shamelin Perkasa, 3.5 Miles Cheras, 56100 Kuala Lumpur, Malaysia.

Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attrib ution License 4.0 International License 2011 by a massive magnitude 9 earthquake (centred offshore to the northeast of Honshu Island) and by the subsequent historic tsunami of March 11, 2011.Because of the resulting nuclear meltdown, the hydrogen-explosion damage to the buildings that housed the reactors, and the contamination of the cooling water from the reactor cores, large quantities of radioisotopes were emitted into the atmosphere and adjacent seawater.From November 22 to 23, 2012, the Tokyo University of Marine Science and Technology independently sampled radioisotope levels in fishery species off Iwaki-Shi (Iwaki City), Fukushima-Ken, just south of the former nuclear power plant.These data included detailed measurements of individual fish such as weight, sex, length, and collection site, which can be used to better understand the accumulation of radioisotopes in fishes.This report shows new insights into the relationship between the accumulation of specific nuclides (radioisotopes) by specific fish species based on this sampling after Katsura's report (Katsura, 2013a;Gerhard et al., 1998;Hellstrom and Brune, 1964;Kalmun, 1982;Murray, 1962;Wolfson, 1956) (Figure 1).

MATERIALS AND METHODS
To sample local fish, trawl (dragnet) fishing was conducted on the November 22, 2012, off Yotsukura and Ena, Iwaki-Shi, Fukushima-Ken, Japan, in a total fishing area of 9,450 and 9,775 m 2 , respectively (Atkins and Warren, 1953).Gill-net fishing was conducted from November 22-23, 2012 in the same location, with a total fishing area of 28,900 and 50,141 m 2 off Yotsukura and Ena, respectively (Buscaino et al., 2009).The edible portion of sampled fish was minced and placed into 100 ml plastic containers (U-8 containers).The concentration of Cs-134 and Cs-137 radioisotopes in the fish biomass were measured by IDEA Consultants Inc. (Tokyo, Japan) using a germanium semiconductor detector (Seiko EG&G Co.Model:GEM20-70) (Inazu et al., 2011;Minatani et al., 2012).

RESULTS AND DISCUSSION
The total fish-collection area for November 22-23, 2012 as shown in Table 1 was calculated as follows (Katsura, 2013b): 9,450+28,900+9,775+50,141= 98,266 m 2 Table 2 shows the following: i) [Percentage of Total Fish Weight] = [%TFW] is the percentage that each species of fish has with respect to the total fish weight sampled.
ii) ([134Cs per Fish Species] / [Total 134Cs for All Species]) × 100 is the percentage of 134Cs becquerel that each fish species has of the total 134Cs becquerel for all fish species (Bq is the symbol for "becquerel", an SI derived unit of radioactivity; One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second) (Choppin et al., 2002).
iii) ([137Cs per Fish Species]/[Total 137Cs All Species]) is the percentage of 137Cs becquerel that each fish species has of the total 137Cs becquerel for all fish species sampled.iv) Tables 3 and 4 show the proportion of 134Cs and 137Cs accumulated by each fish species according to their percentage of the total fish weight in descending order, as follows: If there was a proportional relationship between the amount of 134Cs or 137Cs Bq (that is, quantity of 134Cs or 137Cs radioactive material) in sampled fish body weight regardless of species, all percentages of 134Cs or 137Cs Bq per percentage of total fish weight should be 100% (Table 5).These findings indicate that these fish species do not have the ability to accumulate 134Cs and 137Cs radioisotopes.In other words, these species eliminate 134Cs and 137Cs radioisotopes from their bodies.iv) Tables 3 and 4 show the differences in the 134Cs and 137Cs accumulation ratio depending on fish species; some species accumulate more 134Cs whereas other species accumulate more 137Cs.
Thus, the order values of of Ditrema temminkii (Surfperch; Japanese Name: UMITANAGO) is higher than that of Cynoglossus joyneri (Red tongue sole; AKASHITA BIRAME) (Figure 4) and the order value of:   v) Additionally, Tables 3 and 4 show accumulation ratio differences between adult fish and fry of the same species.Each species of fish has how much weight percent of total fish weight in this sampling in offshore Fukushima-ken, Japan in November 2012.
vi) It is currently known that specific fish species have the ability to accumulate specific elements, ions and molecules (Thompson et al., 1972).However, the accumulation of specific radioisotopes had not been reported until this and Katsura's research article (Katsura, 2013a).The disaster at Fukushima on March 11, 2011 provides the opportunity to gain new insight into the accumulation of specific radioisotopes by fishes.We must discover the theoretical reasons for these phenomena in order to use fishes as new methods for atomic fuel production and clean-up of specific radioisotope contamination.4) Physical methods such as ultra-centrifugation and diffusion have been used to obtain high concentrations of nuclides (e.g., 235 U).This study suggests that physical methods are not required to accumulate high concentrations of specific radioisotopes.

Table 1 .
Total fish collection area on 22 to 23 November, 2012.

Table 2 .
Amount of fishery resources and the total amount of cesium radioisotopes in fish bodies in offshore Fukushima-Ken, Japan in Nov. 2012.
Ditrema temminkii for 134Cs.Therefore, it may be possible to use Ditrema temminkii and Cynoglossus joyneri for the accumulation or