碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 92 / Cutlassfish, Trichiurus lepturus Linnaeus, is one of the most common and important commercial marine fish species in China seas since about 60～80% of the world productions are landed in the East China Sea and Taiwan’s offshore/coastal waters. Many studies on cutlassfish have been well documented based upon only one species（T. lepturus）although there are three reported species （T. lepturus, T. brevis, and T. nanhaiensis） distributed in the China seas. Furthermore, the cutlassfish resource has also suffered from serious overfishing. Mainland China has now exercised seasonal (May to July) closure in East China Sea and South China Sea but their scientific bases are not well documented. Therefore, the aim of this study is to investigate the growth and reproduction of cutlassfish species in the waters off Taiwan. A total of 2085 specimens of T. lepturus and T. nanhaiensis were collected monthly from August 2002 to September 2003, mainly from Tashi and An-ping as well as lesser samples from NanFangAo, ChengGong, DongKang, LienJiang fishing port.
Ages were estimated using sagittal otolith transverse sections. And, opaque growth rings were validated that formed once per year during February and December to January for both T. lepturus and T. nanhaiensis respectively. According to the age counts and preanal length measures which fitted with the von Bertalanffy growth model, resulting in：
PLt（mm）= 508.27 {1- e [-0.269 ( t + 1.775 )]} （T. lepturus）
PLt（mm）= 625.80 {1- e [-0.168 ( t + 2.142 )]} （T. nanhaiensis）
The growth of the two species were significantly different.
From examining the ovaries macroscopically, whole oocytes microscopically, and Gonosomatic Index/Hepatosomatic Index, it is suggested that there are two peaks of spawning period for T. lepturus in the waters off Taiwan. The majority was during February to July and another one was November to December. T. nanhaiensis was spawn during April to August. The mean preanal length at sexual maturity of females T. lepturus in the waters off Taiwan were 256mm. The sex ratios of both species were significantly different from 1：1。
| Identifer | oai:union.ndltd.org:TW/092NTOU5451015 |
| Date | January 2004 |
| Creators | SHIH Nien-Tsu, 石念祖 |
| Contributors | NI I-Hsun, 倪怡訓 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 102 |
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