Reproductive cycles ofSebastes taczanowskii,compared with those of other rockfishes of the genusSebastes |
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Authors: | Hiroya Takahashi Kazunori Takano Akihiro Takemura |
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Institution: | (1) Department of Biology, Faculty of Fisheries, Hokkaido University, 041 Hakodate, Hokkaido, Japan |
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Abstract: | Synopsis Seasonal reproductive cycles were examined in both sexes ofSebastes taczanowskii, captured in southern Hokkaido, Japan. The reproductive cycle in females was divided into four periods: recovery (July–August),
vitellogenesis (September–March), gestation (April–May) and parturition (June). Spermatozoa were first observed in November
in the ovarian cavity, where no structural specialization was present for sperm storage. Fertilization of oocytes appeared
to occur in April, when the oocytes underwent a rapid process of final maturation. Embryos developed in the ovary quite synchronously
and were released in June; empty ovaries indicated the rockfish has a single parturition. The reproductive cycle in males
comprised five periods: resting (December–July), early maturation (February–May), mid-maturation (June–August), late maturation
(September–October) and functional maturation (November). In November when active spermatogenesis had been completed, a large
amount of spermatozoa was preserved in the sperm duct, and the males were therefore ready for mating. A comparison was made
of the reproductive cycles of four species of the genusSebastes inhabiting southern and northern waters of Japan. It suggests that the northern species tend to prolong gametogenesis in
both sexes while the southern species have the opposite tendency. Sperm storage in the ovary also tends to be longer in the
northern than in the southern species. |
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Keywords: | Ovarian cycle single parturition Sperm storage Testicular cycle Viviparity Pisces Scorpaenidae |
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