Breeding ecology of an amphidromous goby of the genusRhinogobius |
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Authors: | Daisuke Takahashi Yasunobu Yanagisawa |
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Institution: | (1) Laboratory of Animal Sociology, Faculty of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, 558-8585 Osaka, Japan;(2) Department of Biology, Faculty of Science, Ehime University, 2-5 Bunkyo-cho, 790-8577 Matsuyama, Japan |
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Abstract: | Field observations of markedRhinogobius sp. DA (Dark type) individuals and monthly sampling in the Kashiwa River, Shikoku Island, Japan, indicated the breeding season
of the species to be from mid-April to early July, peaking in May. Mark-and-recapture data showed that at least half of the
females spawned more than once in one breeding season. Although eggs in male-guarded nests were all at the same developmental
stage, their mean number exceeded that of pre-spawning yolk stage oocytes per female, suggesting that at least some guarding
males received eggs from more than one female. The physical condition of both sexes deteriorated considerably during the breeding
season, the hepatosomatic index of guarding males decreasing concurrently with the development of eggs. The decline in physical
condition of guarding males was attributed mainly to their restricted feeding opportunities. |
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Keywords: | Rhinogobius breeding season fecundity parental care physical condition |
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