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Original data (Cs and Cs, and sampling location) of marine products in Fukushima Prefecture monitored during 2011-2015 (n = 32,492) were analyzed to present an updated detailed description of radiocesium contamination after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident and to examine taxon/habitat-specific decreasing trends in different areas. Furthermore, marine species data presented by the Tokyo Electric Power Company (TEPCO) during 2012-2015 (n = 5458) were analyzed to evaluate the decreasing trends ofCs inside and outside (within a 20 km radius) of the FDNPP port. Monitoring results by Fukushima Prefecture show that percentages of samples higher than the Japanese regulatory limit of 100 Bq kg-wet (>RL%) were higher, whereas those below the detection limit (RL% and

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Habitat utilization, feeding, and growth of a rare pleuronectid flatfish, spotted halibut Verasper variegatus, were examined in a brackish lagoon in northeastern Japan: Matsukawa-ura. The distribution and date-length data of spotted halibut collected mainly from beam-trawl samplings during 1983-2008 indicated that age-0 juveniles [n = 25, 6.0-18.0 cm total length (TL)] and older spotted halibut (n = 71, 13.8-43.0 cm TL) inhabited almost the entire northern part of Matsukawa-ura. Comparative distribution surveys of spotted halibut, stone flounder, and marbled flounder during 1985-1989 revealed similar distribution patterns of these flatfishes; the highest densities were found around the central part of Matsukawa-ura, although significantly lower abundance was detected for spotted halibut. Linear growth equations of age-0 juveniles demonstrated that spotted halibut were able to achieve high growth after June, probably because abundant prey (e.g., mysids and gammarids) and suitable physical conditions (warmer water temperature and lower salinity) were present. The main prey items shifted from various crustaceans including mysids, caridean shrimps, and anomurans to brachyura Hemigrapsus spp. (C20 cm TL). Our study shows that spotted halibut use the shallow brackish lagoon as an important nursery for juveniles, and also as a feeding ground for young and adults.

We examined the genetic population divergence of the spotted halibut Verasper variegatus. A previous report suggested two conservation units for this species along the Japanese Pacific coast. Extending the coverage of the genomes (29 microsatellites and three mitochondrial DNA segments) revealed hitherto-undetected genetic population boundaries. We screened population samples from the major habitats along the Japanese coast and the Yellow Sea coast (East Asian Continent). Significant genetic differentiation was found in every comparison between the habitats. In most cases, the nuclear and mitochondrial population divergences were incongruent, most likely caused by differences between the two genomes in the effects of genetic drift after recent population isolation and bottleneck events. We discuss the ecological and evolutionary mechanisms of the genetic structure as well as the units of conservation. The present study illustrates the merits of wider coverage of genomes in genetic population analysis especially for species with a shallow population history.