著者

加賀 豊仁 尾田 紀夫

出版者

[栃木県水産試験場]

雑誌

栃木県水産試験場研究報告 (ISSN:13408585)

巻号頁・発行日

no.48, pp.37-46, 2005-03

被引用文献数

1

---

栃木県では、大田原市羽田地内、大田原市滝岡地内、矢板市山田地内及び匿名のA生息地の4ヵ所の水路又は沼にミヤコタナゴの生息が確認されている。ミヤコタナゴ生息地の物理的、化学的環境は異なり、保全事業の実施にあたってもそれぞれの特性に応じた対応が必要である。羽田生息地は環境省により保護地に指定されているが、水源である羽田沼は周辺開発や飛来する水鳥の影響等により富栄養化が進み、底泥の堆積も顕著になっている。ミヤコタナゴ生息水路に流入する懸濁物質は緩流部を中心に堆積し、ミヤコタナゴ産卵母貝であるマツカサガイの生息域を減少させ、ミヤコタナゴの生息そのものを阻害する可能性がある。また、アンモニア態窒素をはじめとする栄養塩類は水生植物の植生変化を惹起し、水路形態の変化につながる可能性が推察される。本水域においては定期的な水質測定が実施されておらず、その現況把握とともに季節変化の把握によりミヤコタナゴ生息環境の保全を検討することが必要である。このため、水源の羽田沼流出部及び生息地水路の数地点において水質の流程変化及び季節変化を調査した。

著者

福冨 則夫 中村 智幸 土居 隆秀 武田 維倫 尾田 紀夫

出版者

The Ichthyological Society of Japan

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

vol.49, no.1, pp.53-58, 2002-05-24 (Released:2010-06-28)

参考文献数

16

---

Twenty-one specimens of the Pacific lamprey, Entosphenus tridentatus, were collected from the Hoki (8 specimens), Yusaka (11 specimens) and Arakawa Rivers (1 specimen), all tributaries of the Naka River, and the mainstream of the Naka River (1 specimen), Tochigi Prefecture, central Japan, between August 1999 and April 2001. Seven spawning redds, possibly constructed by Entosphenus tridentatus, were found in the Yusaka River on May 2 and 11, 2000, eggs being observed in one of them. Two specimens, collected from the Yusaka River and reared in an aquarium with a gravel substrate, subsequently spawned about 1000 eggs being observed in the redd. Forty-one of the eggs were reared at 15°C in an electric incubator, hatching starting 13-17 days after spawning. The hatching percentage was 92.7%, the accumulative temperature to hatching being between 195 and 255°C.

著者

伊藤 寿茂 尾田 紀夫 丸山 隆

出版者

日本生態学会

雑誌

日本生態学会誌 (ISSN:00215007)

巻号頁・発行日

vol.53, no.3, pp.187-196, 2003-12-25

被引用文献数

6

---

Availability of host fish for glochidia of the freshwater unionid mussel Pronodulariajapanensis was examined for the following eleven species of fish: Zacco temminckii, Phoxinus longowskii steindachneri, Gnathopogon elongatus elongatus, Pseudorasbora parva, Cyprinus carpio, Tanakia lanceolata, Acheilognathus tabira subsp. R, Misgurnus anguillicaudatus, Pseudobagrus tokiensis, Rhinogobius sp. OR and Gymnogobius urotaenia. The hosts to which the glochidia were attached in a paddy field ditch were cultured in tanks for seventeen days. Glochidia and juveniles which became detached from the hosts were counted daily. Juveniles appeared about nine days after glochidia attachment. Rhinogobius sp. OR, G. urotaenia, Z. temminckii and C. carpio were the most suitable hosts on which over 69% of attached glochidia metamorphosed to juveniles. Three hosts, G. e. elongatus, M. anguillicaudatus and Rhinogobius sp. OR, were investigated as to the position and number of attached glochidia. Most glochidia were attached to fish fins and gills. More glochidia were attached to Rhinogobius sp. OR than to the other species. However in the study ditch, M. anguillicaudatus was most numerous and therefore the major host species.