碩士 / 國立臺灣海洋大學 / 海洋事務與資源管理研究所 / 102 / Fisheries resources support an essential part of food security for human. However, the stock biomass of most commercially exploited target species, at least 78% of status of the stock was evaluated as full- or over-exploitation. At the same time, global production of cephalopods was increased in the past four decades. The cephalopod was suggested as one of the marine resources which could support fishery development in the world. Understanding life-history traits and population structure of exploited stock of cephalopods was critical to form strategy for effective fisheries management. Most of the current studies was focused on commercially important target species (particularly squids), yet less studies for cuttlefish. Studies of cuttlefish in Taiwan were major in experiments in laboratory, while less study in species composition and population structure in field. The Yilan Bay is one of the important fishing grounds for the trawl fishery around North Taiwan. Seasonal variation of oceanographic conditions was significant in the Yiland Bay for its topological structure and currents systems. The objectives of this study are: (1) to explore species composition of cuttlefish in Yilan Bay and its seasonal variation pattern; (2) to study life-history traits of the dominant cuttlefish species. The samples of cuttlefish were collected from a trawl vessel monthly from Dasi fishing port (Yilan County) from January 2011 to June 2013. The features used for identification of cuttlefish species are: color patterns of skin, number and size of suckers of tentacle clubs, and structure and shape of cuttlebone. A total of 1903 individuals (207.4 kg) of cuttlefishes was collected during the studied period which encompassed ten species. The five most frequent species are: Sepia esculenta, S. madokai, S. pharaonis, S. tenuipes, and Sepiella japonica. Production and species diversity of cuttlefish was higher in cold-water season (from November to March). The dominant species varied by season, S. esculenta dominated in cold-water season, while S. madokai dominated in warm-water season (from May to September). ML of S. esculenta increased from August to next January. Fitting monthly ML composition to von Bertalanffy growth function, the maximum ML for female and male S. esculenta was estimated at 180 mm with a lifespan of ca. 27 months. Higher GSI values of female and male for S. esculenta occurred in November and January which suggesting they might spawn in spring. ML-at-maturity for females (114 mm) was higher than males (109 mm). S. madokai usually occurred in warm-water season, while the sample size was too few to conclude information in life-history traits. ML-at-maturity for females (87 mm) was higher than males (61 mm). Seasonal variation in species composition of cuttlefish in Yilan Bay could be influenced by oceanographic conditions which dominated by different water mass seasonally.
| Identifer | oai:union.ndltd.org:TW/102NTOU5277005 |
| Date | January 2014 |
| Creators | Zih-Heng You, 游子恆 |
| Contributors | Chen, Chih-Shin, 陳志炘 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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