碩士 / 國立臺灣海洋大學 / 海洋事務與資源管理研究所 / 104 / The diversity and assemblage of demersal fish, as well as spawning, condition and feeding cycles of the dominant fish species were examined using bi-weekly or monthly samplings and daily catch records from small bottom trawlers operate in surroundings waters of the Three Northern Isles, Taiwan between Nov. 2012 and Dec. 2015. Results indicated that bycatch (both in number and weight) from these vessels was on average, about 50% of the total. These bycatches included ~20-30% (in number), and more than 50% (in weight) of economical important fish species. The species richness, evenness and diversity were higher both for economically important and bycatch species from end of summer to fall or early winter period (i.e., Sept.-Dec or Sept.-Jan.), while they were lower between end of spring to summer period. The percentage of juvenile bycatch also was higher between end of summer to winter, and lower during the spring, which was opposite with that seen in adult fish. Two fish assemblages been identified were roughly corresponding to cooler (i.e., Sept.-Mar.), and warmer (i.e., Jun.-Aug.) seasons for both economic and bycatch species, and these assemblages were not structured by habitat types or water depths. The spawning season of most fish species occurred in the spring and summer. Most fishes also showed high feeding activity during summer-fall period, and reached highest condition factor in the fall, with a second in summer. The optimum exploitation and management strategies including implementation of close season during the spring and summer to protect spawner, and explore the resources with additional mesh size limitations during the fall when most fishes were plump, and juvenile fishes were abundant, are then suggested accordingly to ensure the sustainable use of the demersal fishery resources of the region.
| Identifer | oai:union.ndltd.org:TW/104NTOU5277003 |
| Date | January 2016 |
| Creators | Chen, Yu-Sheng, 陳育生 |
| Contributors | Wang, Shyh-Bin, 王世斌 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 105 |
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