碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 100 / The sword tip squid, Uroteuthis (Photololigo) edulis, is one of the important economic species in northeastern Taiwan waters. Resources of squids became less and less, thus lead to the decrease of squid production. Currently, the most researches of squids focused on the relationship between catches of torch-light fishery and fishing environments, as well as biological study of squids which caught by torch-light fishery. Trawl fishery is also one of the main fisheries that caughtes squids. Because trawl fishery is inaccessible to random sampling, the fisheries management of squids is dominated by torch-light fisheries. In order to explore the differences of sword tip squid caught by two kinds of fishing methods, this study first compared the biological differences of squids caught by trawl fishery and torch-light fishery. According to Liao (2004) and Hung (2007), the fishing grounds of squids were divided into two parts of dividing line with 122.3 °E and 26 °N, one was offshore and close to the upwelling waters; the other was offshore farther to frontal waters. In this study, we also compared with different fishing grounds in northeastern Taiwan waters. We collected 4,558 specimens of squid (female: 1,973, male: 2,405, juvenile: 180) from torch-light fishery and 9,797 specimens (female: 3,197, male: 3,334, juvenile: 3,266) from trawl fishery in the northeastern waters of Taiwan. The results showed the distribution range of mantle length in trawl fishery (1.8~40.82cm) was wider than the range of torch-light fishery (2.1~32.9cm). Squids that caught in upwelling area were larger than the squids caught in frontal area, and had more mature individuals. The sex ratio showed the squids caught by torch-light fishery had more males with significant sex difference, but no significant sex difference about 1:1 in trawl fishery. The monthly variation of GSI showed that both area of the male squids had a peak value in spring and autumn. In addition, the results of mantle length at 50% sexual maturity excluding spring showed the squids caught in trawl fishery were bigger than torch-light fishery. The 50% sexual maturity also showed the squids caught in upwelling area were larger than frontal area. Exponential and power growth models explained the fit to the size-at-age data to a similar extent. Furthermore, the squids that caught by trawl fishery had higher relationship than the squids caught in torch-light fishery.
| Identifer | oai:union.ndltd.org:TW/100NTOU5451009 |
| Date | January 2012 |
| Creators | Tzu-Ying Chen, 陳姿瑩 |
| Contributors | Cheng-Hsin Liao, 廖正信 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 81 |
Page generated in 0.0136 seconds