Annual changes in oocyte development in the ovary and serum vitellogenin, an egg yolk precursor, were investigated in the rabbitfish, Siganus canaliculatus, in Okinawa, southern Japan. The progres sion of oocyte development was histologically divided into eight stages; the chromatin-nucleolus, peri nucleolus, oil-droplet, primary yolk, secondary yolk, tertiary yolk, migratory nucleus and maturation stages. The oocytes laden with yolk first appeared in March. From April through June, the stage compo sition of oocytes was characterized by a high percentage of oocytes advanced beyond the primary yolk stage and was correlated with the increase of gonado-somatic index (GSI). Post-ovulatory follicles could be observed in the ovaries in May. The GSI values gradually decreased after June and were main tained at low levels from October through February. During these months, the ovaries were occupied by the immature oocytes at the chromatin and peri-nucleolus stages. Vitellogenin, which was measured immunologically with rabbit anti-rabbitfish vitellogenin antiserum, changed in accordance well with the monthly fluctuation of GSI as well as development of oocytes laden with yolk. These results suggest that S. canaliculatus starts vitellogenesis in March and spawns several times in the following three months in Okinawa.
A major spawning of the seagrass rabbitfish Siganus canaliculatus occurred 4 days after the new moon in both May and June 1993, and 7 days after the new moon in 1994. The gonadosomatic index (I G ) and serum vitellogenin (VTG) levels fluctuated according to the lunar cycle; I G and VTG levels showed peaks at around the new moon and the waning moon, respectively, suggesting that spawning of this species is synchronized with the lunar cycle. Vitellogenic oocytes appeared on day 2 after the first spawning and were fully mature on day 30. When a greater percentage of the most advanced oocytes attained the tertiary yolk stage, they formed a batch and separated from the adjacent group of smaller pre-vitellogenic oocytes, indicating that S. canaliculatus is a multiple spawner with an ovary belonging to the group-synchronous type of oocyte development. Batch fecundity, assessed using batches of oocytes at and after the tertiary yolk stage, ranged from c. 0·52 to 2·56 million eggs. The relationship between batch fecundity (F) and fork length (L) can be represented as F=0·0536854L 5·07292 . 1999 The Fisheries Society of the British Isles
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.