Japan Fisheries Research and Education Agency (FRA) Repository
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東京湾湾口部館山湾におけるウツボの食性とその季節変動
Get PDFThe diet and feeding habits of the Kidako moray eel Gymnothorax kidako in Tateyama Bay, Chiba Prefecture, Japan were investigated. Of 348 specimens collected in traps, 214 had empty stomachs. Prey of the remaining specimens included teleosts, cephalopods, crustaceans, and polychaetes, evidence of the carnivorous role of the former, feeding primarily on fishes. Notably, predation of tetrodotoxin-possessing species, such as the grass puffer, implied a potentially significant impact of G. kidako on reef ecosystems. Additionally, seasonal variations were apparent in the gastric emptying rate of G. kidako, suggesting differing feeding activities during the breeding and non-breeding seasons. To precisely evaluate the feeding habits of G. kidako in Tateyama Bay, future research should carefully consider sampling methods, so as to ensure a sufficiently large sample size for a comprehensive study.journal articl
ブリ養殖における人工種苗の生産技術と育種技術の開発
Get PDFブリ養殖は，日本で最も古くから行われている海面養殖である。近年では，国内供給の安定と輸出の拡大を両立する上で重要視されており，生産技術の向上が必要とされている。しかし，現在，ブリ養殖では主に天然の稚魚"モジャコ"が用いられており，生産量はその漁獲量に左右される状況にある。一方，我が国では1960年代から人工種苗の生産に関する研究開発が続けられており，最近では周年にわたって種苗を供給する体制が確立しつつある。本稿では，これまでの人工種苗生産の技術開発の流れを紹介するとともに，今後の方向性について展望する。journal articl
水素細菌を活用した養殖飼料開発
Get PDF養魚飼料用の魚粉の供給不安や価格高騰から様々な新規代替原料の開発が進められている。そのうち細菌類は単細胞タンパク質とも呼ばれ、高タンパク質含量と良好なアミノ酸組成から飼料タンパク質源として期待されている。われわれの研究グループでは、水素をエネルギー源として無機物からすべての有機物を合成できる独立栄養細菌である水素細菌の飼料利用に取り組んでいる。実験室規模での菌体増殖や成分の解析等から、水素細菌も将来的には飼料用のタンパク質源として生産や利用が可能であると考えられた。加えて、水素細菌には生体高分子の合成や炭素固定など別の用途も想定されるため、異分野の研究・産業とも連携や開発した技術の共有が期待される。journal articl
New moon spawning of Acropora divaricata in the Sakishima Islands, Japan
Get PDFMany species of Acropora corals spawn simultaneously around the full moon in early summer (May to June in Japan). Nonetheless, there are some species that delay from this simultaneous spawning and spawn in midsummer (August in Japan). Among them, we focused on Acropora divaricata and investigated the oocyte maturation period in the field and directly observed spawning in tanks. The maturation period peaked in late summer, and all the colonies we directly observed over the three years (36 colonies in total) spawned within two days before or after the new moon. Among the more than several dozen species of Acropora corals reported so far, no species is known to spawn associated with the new moon in tropical and subtropical regions. The reason for this unique spawning timing is unknown, but it is clear that diverse spawning phenology exists within Acropora corals.journal articl
Change in the subtidal reef fish assemblage at Kuchierabu-jima Island, southern Japan, between 1972 and 2005
Get PDFChange in the subtidal reef fish assemblage at Kuchierabu-jima Island, southern Japan, since the 1970s was investigated using an underwater visual census in October 2005. A comparison of this survey with data from 1972 revealed that the frequencies of species that had either increased, remained stable, or declined in abundance were dependent on the geographic range category and the major feeding guild. Temperate herbivorous fishes had noticeably declined in abundance, while subtropical carnivorous species had increased. We discuss causes of the change in the reef fish assemblage from the aspect of water temperature, loss of macroalgal beds, and anthropogenic impacts.journal articl
AIとスマホアプリで魚の全長を推定する
Get PDF2023年11月15日、国立研究開発法人水産研究・教育機構が、第20回成果発表会を開催しました。同機構ではさまざまな形で調査研究の成果の普及に努めていますが、そのひとつとして、広く一般の方々を対象とした成果発表会を開催しており、本年度（令和６年度）は、「水産研究・教育機構の取り組むスマート水産業」として、漁業現場の課題解決に向けた、AIやIoTなどのデジタル技術を活用した、５つの研究開発の成果を発表しました。本誌では発表されたそれぞれの成果の内容について毎月掲載してきます。journal articl
Detailed kinship estimation for detecting bias among breeding families in a reintroduced population of the endangered bagrid catfish Tachysurus ichikawai
Get PDFIn the context of initiatives focused on captive breeding and reintroduction of endangered animal species, it is crucial to minimize any bias in reproductive success during the reintroduction phase in order to preserve genetic diversity. One population of Tachysurus ichikawai, a critically endangered bagrid catfish endemic to Japan, faces a threat from the construction of a dam. To address this, a captive breeding program followed by translocation is being implemented. Multiple breeding families are involved in this process; however, if there is a bias in reproductive success among them after release, it will result in a decline in genetic diversity. To ascertain potential biases of reproductive success among released individuals, we attempted to identify the familial lineage of individuals born at the release site. Due to the unavailability of samples from the released individuals themselves, we reconstructed the pedigree of three generations using distant kinship relationships, such as grandparent–grandchild and uncle–aunt–nephew–niece relationships, with data of 2230–5674 single-nucleotide polymorphisms obtained from whole genome re-sequence, and three different software. Our findings indicate no bias between lineages in the first year after reintroduction, but a significant bias in the second year, emphasizing the need for continuous management and monitoring of reintroduced populations. This study demonstrates that monitoring kinship after reintroduction can correct lineage bias, which is critical for the prompt restoration of genetic diversity.journal articl
