ホトケドジョウの初期飼育条件 [in Japanese] Early Rearing Conditions of Hotoke loach, Lefua echigonia [in Japanese]
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1) 環境庁と神奈川県の絶滅危惧種に指定されたホトケドジョウの種苗生産技術の開発を行った。<BR>2) 100<I>l</I>PC水槽で, 水温上昇と長日処理により成熟させ, 数種の水草を用いて自然産卵させた。ウイローモスに最も多く産着卵が確認されたが, キンラン (人工水草) にも産卵が確認された。<BR>3) 循環ろ過式の2tFRP水槽で雌雄10尾ずつ親魚を放養し, キンランを用いて, 自然産卵させた。1歳魚の親魚から2, 179尾, 2歳魚から452尾のふ化仔魚が得られた。<BR>4) 県下, 6系統のふ化仔魚の飼育を循環ろ過式の56<I>l</I>ガラス水槽で行った。給餌はシオミズツボワムシ・アルテミア・微粒子飼料を与えた。50～100日間で生残率12.3～77.0%, 体長2～3cmの種苗を育成した。<BR>5) 36<I>l</I>ガラス水槽を用いて初期飼料の検討試験を行い, ワムシを省きアルテミアと微粒子飼料の併用で飼育が可能であった。<BR>6) 2tFRP水槽3面を用いて, 循環ろ過式によりふ化仔魚の飼育を行った。アルテミアと微粒子飼料を給餌し, 121～144日間で約5, 000尾の種苗 (3cmサイズ) を育成した。
We have developed technology for producing seeding of the Hotoke loach, <I>Lefua echigonia</I>, designated as an endangered species by the Environment Agency and Kanagawa Prefecture. In selective of spawning bed experiment, Hotoke loaches were matured in a 100<I>l</I> PC tank with increased water temperature and long-day treatment, and natural spawning was induced using several types of aquatic plants. While the highest spawning was achieved with Uiromosu, <I>fantinalis antipyreticus</I>, spawning was also observed with Kinran, an artificial water plant. In experiments of mass egg-taking, designed to increase production, batches of 10 male/female parent fish were released into a 2tFRP tank with circulating filtration, and spawning was induced using Kinran. A total of 2, 179 hatched larvae were obtained from 1-year-old parents and 452 from 2-year-olds.<BR>We conducted rearing trials using the hatched larvae. Hatched larvae, breeding experiments under prefectual administration, we reared six groups of hatched larvae in 56<I>l</I> glass tanks with circulating filtration. Between 60 and 300 larvae were accommodated in each tank and were fed rotifer, <I>Aytemia</I>, and particulate feed. The survival rate between 50 and 100 days was 12.3-77.0%, and seedlings with a body length of 2-3cm were produced. In hatched larvae food experiment, we conducted a study trial on initial feeding in a 36<I>l</I> glass tank. We found that the larvae could be reared with a combination of <I>Artemia</I> and particulate feed, excluding rotifers. In experiments of mass seed production, aimed at increased production, we reared hatched larvae via circulating filtration in three 2tFRP tanks. With a combination of <I>Artemia</I> and particulate feed, approximately 5, 000 seedlings (3cm size) were produced between 121 and 144 days.
- Aquaculture Science
Aquaculture Science 50(1), 55-62, 2002-03-25
Japanese Society for Aquaculture Science