碩士 / 國立海洋大學 / 漁業科學學系 / 90 / Stock assessment of the bigeye thresher shark, Alopias superciliosus in the northeastern waters off Taiwan was conducted with demographic approach: stage based model and age-structured model. Four life stages of A. superciliosus was determined based on its biological characteristics as neonate, juvenile, pregnant adult and resting adult. Natural mortality of each stage estimated from Peterson and Wroblewski (1984) was as follows: M1=0.175, M2=0.121, M3=0.108, M4=0.108 yr-1. The results of stage-based model indicated that the finite rate of population increase λ= 1.05, intrinsic rate of increase r= 0.049 withuot fishing mortality, while the bigeye thresher stock decreased slowly (λ=0.94, r=-0.065) under current fishing condition. Similar results were obtained from age- structured model. The results of stochastic stage-based model indicated that the bigeye thresher stock is declining (λ=0.929 with 95% C.I.=0.882~0.975) under current fishing condition and will reduce 52.4% and 77.3% for 10 yr and 20 yr projection, respectively. The stock is sustainable as long as fishing mortality maintains 0.067yr-1 that is exploitation rate E=37% or neonate and juvenile stages was protected.
| Identifer | oai:union.ndltd.org:TW/090NTOU0451007 |
| Date | January 2002 |
| Creators | LIN SHIH HUA, 林世華 |
| Contributors | 劉光明 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 75 |
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