Fukushima Prefecture History Museum

ABSTRACT Four Pseudarchasteridae species, including one new species, are described from Japanese waters. Paragonaster hoeimaruae Kobayshi sp. n. resembles two north-west Pacific congeners, P. chinensis and P. obtusus, but differs from these species in having pedicellariae and lateral abactinal series extending to less than one-half of arm length. We also report the first occurrence of Gephyreaster and P. stenostichus from Japanese waters. http://www.zoobank.org/urn:lsid:zoobank.org:pub:0B02F074-9B9A-4A87-A9D5-797740C6EE50

Pacific saury (Cololabis saira) is a commercially important small pelagic fish species in Asia. In this study, we conducted the first-ever whole genome sequencing of this species, with single molecule, real-time (SMRT) sequencing technology. The obtained high-fidelity (HiFi) long-read sequence data, which amount to ~30-folds of its haploid genome size that was measured with quantitative PCR (1.17 Gb), were assembled into contigs. Scaffolding with Hi-C reads yielded a whole genome assembly containing 24 chromosome-scale sequences, with a scaffold N50 length of 47.7Mb. Screening of repetitive elements including telomeric repeats was performed to characterize possible factors that need to be resolved towards 'telomere-to-telomere' sequencing. The larger genome size than in medaka, a close relative in Beloniformes, is at least partly explained by larger repetitive element quantity, which is reflected in more abundant tRNAs, in the Pacific saury genome. Protein-coding regions were predicted using transcriptome data, which resulted in 22,274 components. Retrieval of Pacific saury homologs of aquaporin (AQP) genes known from other teleost fishes validated high completeness and continuity of the genome assembly. These resources are available at https://treethinkers.nig.ac.jp/saira/ and will assist various molecular-level studies in fishery science and comparative biology.

A new species of the genus <i>Hynobius</i> from the central part of Tohoku District, Japan, is described. <i>Hynobius lichenatus</i> was divided into three groups based on morphological and molecular analyses, and the boundaries of these groups were delineated. The central part of the Tohoku group was described as <i>Hynobius senzanensis</i> sp. nov., whereas populations from the southern part of Tohoku, the northern part of Kanto, and the eastern part of Hokuriku were resurrected as <i>Hynobius unanngso</i>. Morphometric comparisons revealed that <i>H. lichenatus</i> possesses significantly shorter vomerine teeth length in both sexes compared with the other two species. Additionally, <i>H. lichenatus</i> exhibited a significantly longer tail length compared with <i>H. unanngso</i>. Although the new species and <i>H. unanngso</i> shared similar morphology, they differed significant in the width of their vomerine teeth, and did not form a sister group as closest relatives. Following this taxonomic reassessment, <i>H. lichenatus</i> is now limited to the Tohoku area (comprising Aomori, Iwate, Akita, and Miyagi Prefectures). The boundary between <i>H. lichenatus</i> and the new species is located in the southern part of Akita Prefecture, along the Japan sea side, and the eastern part of Miyagi Prefecture, along the Pacific Ocean side. This study provides insights into the distribution ranges of the three species and a re-evaluation of their habitat status is crucial for their conservation.

Abstract The reproductive biology of deep-sea fishes is largely unknown because of the difficulty of behavioral observations in this environment. In this study, the reproductive behavior of the deep-sea snailfish, Careproctus pellucidus, which lives at depths &gt; 200 m, was observed in an aquarium. To the best of our knowledge, this is the first report to observe and describe the reproductive behavior of deep-sea fish under free-living conditions. Fishes were collected at a depth of approximately 300 m (36°70′ N; 141°00′ E) on July and August 2018 and kept for observation until March 2019. We observed that almost all spawnings took place between one male and one female. Males defended a spawning substrate against other males and exhibited body-wiggling behavior for both courtship and aggressive display. Females visited the male’s territory and spawned a demersal adhesive egg mass on the substrate. The territorial male then sought the spawned eggs using filamentous rays in the lower pectoral-fin lobe and released sperm when he located the eggs. Males remained near the spawning substrate after spawning but did not perform any parental care. Notably, sneaking behavior by a non-territorial male was observed in one case; this is the first report of this alternative reproductive strategy (or tactic) in a deep-sea fish. Our study reveals the unique reproductive biology of the deep-sea fish, C. pellucidus, which does not depend on visual information and uses other sensory modalities.

Beach sand samples were collected along a coastal area 32 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Fukushima Prefecture, Japan, 5 years after the FDNPP accident. Desorption experiments were performed on the sand samples using seawater in a batch experimental system to understand the forms of existence of radiocesium in sand and their desorption behavior in a coastal environment. The percentage of radiocesium desorption decreased exponentially with an increase in the number of desorption experiments for the four sand samples, with 137Cs radioactivity from 16 to 1077 Bq kg-1 at surface and deeper layers from three sites. Total desorption percentage ranged from 19 to 58% in 12 desorption experiments. The results indicate that the weak adsorption varies with the sampling sites and their depth layer. To understand the desorption behavior of radiocesium in the sand samples, the desorption experiments were performed for a sand sample by using natural and artificial seawater, and NaCl solution in the presence and absence of KCl. The 137Cs desorption from the sand collected at a depth of 100 - 105 cm from the ground surface (137Cs radioactivity 1052 ± 25 Bq kg-1) was 0.1% by ultrapure water, 3.7% by 1/4 seawater and 7.1% by 1/2 seawater, 2.2% by 470 mM NaCl solution (corresponding to a similar concentration of seawater) and 10 - 12% by seawater, artificial seawater and 470 mM NaCl + 8 mM KCl solution. These results indicate that about 10% of radiocesium adsorbed on the sand is mainly desorbed by ion exchange of potassium ion in seawater, though the concentration of major cation, or sodium ion, in seawater makes a small contribution on 137Cs desorption from the sand samples.

Here, we report the results of our preliminary study on deep sea eDNA at fishing ground to approach the fisheries resources abundance at Sulawesi sea by using deep-sea water sampling collected from 10 sites ranging from 110m-200m in depth at front side of the International Coelacanth Research Center and Museum Base at Lolak Waters and Manado Bay North of Sulawesi using Nansen Bottle Sampler (1500 cc). The collected waters were filtered using Power Water Sterivex DNA Isolation Kits and preserved with the DNAiso Reagent then transported to Center for Strategy Research Project, University of the Ryukyus, Okinawa Japan where eDNA analyses were conducted. Our results revealed that the concentrations of eDNA has a good quality were measured with a NanoDrop Lite spectrophotometer, indicating eDNA was successfully extracted. Therefore, by using universal primers for eDNA, MiFish-U-F/R for the 1st-PCR (mt-12S amplification) and 2nd-PCR (tag-indexing) for library preparation to accommodate sequence variations and show that intense signal of MiFish eDNA amplification. Using a high-throughput Illumina MiSeq platform for sequencing analyses, we detected eDNA from 40 fish’s species with dominantly by Caranx sexfasciatus, Encrasicholina punctifer.