碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 102 / Swordfish (Xiphias gladius) is one of an important commercial species in the Indian Ocean. However, due to serious local depletion occurred for swordfish in the southwest Indian Ocean in recent years, the Indian Ocean and Indian Ocean Tuna Commission was very concerned for the over exploitation of this resource. Therefore, this study developed an operation model based on age-structured model and evaluated the future total allowable catch as decision rules through the simulation analysis of management procedure. Three decision rules were applied to explore the projected trends of biomass and total allowable catch under different management aspects. The average annual variability in catch was used to be the performance measure for evaluating the optimal management procedure. The 40% of initial spawning biomass (0.4S0) and spawning biomass at which maximum sustainable yield (SMSY) is achieved adopted to be the reference points for management purpose. The results of this study indicated that the probability of achieving the reference points of 0.4S0 and SMSY would be higher than 50% in 2011 and 2018 for swordfish in the entire Indian Ocean if the exploitation maintained under current level. For swordfish in the southwest Indian Ocean, however, the reference point of SMSY would be achieved in 2027, while the reference point of 0.4S0 would be never achieved. In this study, therefore, three decision rules were applied to the evaluation of management procedure for swordfish in the southwest Indian Ocean. Under decision rule of concerning the variation of biomass, higher catch was available in future 30 years, the average annual variability in catch was lower, but reference points of 0.4S0 cannot be achieved. Under decision rule of achieving the reference points, both reference points of 0.4S0and SMSY can be achieved, but lower catch was available in future 30 years and the average annual variability in catch was higher. Combining two decision rules can achieve both reference points and future catch can be maintained with proper annual variability.
| Identifer | oai:union.ndltd.org:TW/102NTOU5451016 |
| Date | January 2014 |
| Creators | Chang, Ching-Yuan, 張慶媛 |
| Contributors | Wang, Sheng-Ping, 王勝平 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 45 |
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