Age-based demography and sexual pattern of the white-streaked grouper, Epinephelus ongus in Okinawa
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- 作者：Itaru Ohta ; Akihiko Ebisawa
- 关键词：Growth ; Maturity ; Sex change ; Monandric protogynous hermaphrodite ; Sex ratio ; Serranidae
- 刊名：Environmental Biology of Fishes
- 出版年：2016
- 出版时间：October 2016
- 年：2016
- 卷：99
- 期：10
- 页码：741-751
- 全文大小：1,779 KB
- 刊物类别：Earth and Environmental Science
- 刊物主题：Environment
Environment
Nature Conservation
Animal Systematics/Taxonomy/ Biogeography
Zoology
Hydrobiology - 出版者：Springer Netherlands
- ISSN：1573-5133
- 卷排序：99
文摘
The demography and sexual pattern of the white-streaked grouper, Epinephelus ongus (Serranidae), in the Yaeyama Islands, Okinawa, were examined based on age assessment using otoliths and gonadal histology. The von Bertalanffy growth parameters were estimated as follows: L∞ = 34.35 cm total length (TL); K = 0.187 yr. −1; and t0 = − 0.975 yr. The maximum age was 20 yrs. The smallest mature female was 18.9 cm TL, and the age of females at 50 % maturity was estimated to be 3.3 yrs. There were significant differences between sexes in size and age, with males (mean ± SD: 29.2 ± 3.3 cm TL, 9.0 ± 2.7 yr) being larger- and older than females (23.5 ± 3.4 cm TL, 5.9 ± 1.8 yr) Inactive bisexuals appeared in intermediate size and age between both sexes, suggesting that bisexuals were essentially recognized as being in a transitional phase from functional female to male. These facts indicated a monandric protogynous hermaphrodite of the species. Furthermore, transitionals were found only in the non-reproductive period that precedes the spawning aggregation period, indicating that the timing of the sex change has seasonality.