著者

櫻井 真 広瀬 純 四宮 明彦

出版者

日本魚類学会

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

vol.50, no.2, pp.165-168, 2003-11-25 (Released:2011-07-04)

参考文献数

8

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Abstract We conducted underwater observations on courtship and spawning be-haviors of the tetrarogidid fish, Hypodytes rubripinnis in Kyushu Island, Japan. The reproductive behavior and seasonal changes of gonad somatic index on col-lected specimens showed that spawning occurred from late April to early August. Individuals of various sizes in both sexes reproduced in the study area. About 90 min before sunset, a male courted a female actively with several patterns of be-haviors such as male's lying by a female in a side-by-side position, display of his lateral side around a female, and male's riding on a female back. Finally, the pair swam toward 20 to 100 cm above the bottom to release gametes. Spawning time was around sunset. The average egg number in each spawning was about 1600. Upward rush of the pair to the middle water occurred very quickly. Frequent sneaking behavior by another male was also observed.

著者

岸野 底 四宮 明彦 寿 浩義

出版者

日本魚類学会

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

vol.55, no.1, pp.1-8, 2008-05-15 (Released:2012-07-13)

参考文献数

28

被引用文献数

3

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Fasting Ryukyu-ayu (Plecoglossus altivelis ryukyuensis) larvae (newlyhatched, 15-20 day old and 50 day old individuals) subjected to ranges of experimental water temperature and salinity [15-21°C (2 or 3 steps) and 0-30 psu (3 or 4 steps), respectively] showed greatest survival rates in water temperatures of 15-18°C and salinity of 5-15 psu. Such water temperature and salinity ranges paralleled those of brackish water in the Yakugachi River during the early life stages of Ryukyuayu, and supported a field investigation which indicated that Ryukyuayu larvae occurred mainly in brackish water. The experimental result is probably illustrates the limits of osmoregulatory adjustment in larvae of this species.

著者

立原 一憲 四宮 明彦 木村 清朗 今井 貞彦

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.38, no.2, pp.159-167, 1988-08-31

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Observations on the development of aggressive behavior of Japanese perch, Coreoperca kawamebari, were made over a 1-year period. Newly hatched larvae aggregated at the water surface and showed no aggressive behavior. Several days after yolk sac absorption, larvae dispersed from the water surface to the substrate and began to feed and fight. Chasing and lateral displays as seen in adult fish were firstly observed at this time, and a dominance hierarchy was evident at 50 days after hatching. Dominant individuals formed their territories after 50 days and gradually enlarged them as body size increased. The behavioral ontogeny of this fish is divisible into four phases, i. e. aggregation, dispersion, developing of aggressive behavior and territorial phases, and these correspond with four different stages of growth, namely prelarva, postlarva, juvenile and young stages, respectively.

著者

岸野 底 四宮 明彦

出版者

公益社団法人日本水産学会

雑誌

日本水産学会誌 (ISSN:00215392)

巻号頁・発行日

vol.69, no.4, pp.624-631, 2003-07-15

被引用文献数

5 14

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絶滅が危惧されるリュウキュウアユの遡上期の生態を明らかにするため,1994年と1996年に鹿児島県大島郡住用村の役勝川で,遡上個体の出現期間,体長,日齢および発育段階を調査した。遡上期間は1月下旬から5月下旬までの4ヶ月間であった。平均体長(±標準偏差)は35.2±3.36mm,平均日齢は83.7±15.4日であった。外部形態は,黒色粗胞の少ないシラス型後期仔魚から,櫛状歯が出現し始めた稚魚まで多様な発育段階を示した。この結果はアユと比較して,より小型,若齢,早い発育段階を示しており,これらの特徴は遡上前の海域生活期間の短さに関連していると考えられた。