碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 96 / In total, 378 males and 423 females (84 pregnant individuals), collected at Dashi fishing port in Yilan County from June 2006 to December 2007 were used to examine the reproductive biology of Narke japonica in the northeastern waters of Taiwan. A sexes-combined relationship between eviscerated weight (EW; in g) and total length (TL; in cm), was estimated as: EW=0.0629×TL2.5608 (n=798, P<0.05). Sizes at 50% sexual maturity were 20.0 cm and 20.4 cm TL for males and females, respectively. Japanese sleeper ray is an aplacental viviparous species that possess paired functional ovaries and uteri. According to the monthly changes of GSI, monthly average maximum ova diameter, and gravid females without vitellogenic ovarian follicles, a biennial reproductive cycle remains a suitable hypothesis. Gestation lasted approximately one year. In the light of the temporal changes in GSI and proportion of mature spermatocysts, the males have an annual cycle. Size at birth was estimated as 8.0 cm TL based on the largest near-term fetuses and the smallest free-swimming neonates. Litter size ranges 1-9 (mean=4.07± 2.05) and increases with maternal weight linearity The chemical balance of development (CBD) based on the mean dry mass of fertilized eggs and near-term fetuses was about 1.17, suggesting that N. japonica was an incipient histotrophic species. A Chi-square test indicated that the sex ratios of each maturity stage and overall were not significantly different from 1:1 (P>0.05), but unborn individuals was significantly different from 1:1 (P<0.05).
| Identifer | oai:union.ndltd.org:TW/096NTOU5451013 |
| Date | January 2008 |
| Creators | Shiau Wen Lin, 林小雯 |
| Contributors | Shoou Jeng Joung, 莊守正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 129 |
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