碩士 / 國立臺灣大學 / 海洋研究所 / 99 / Thunnus albacares known as yellowfin tuna is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. There are important yellowfin tuna fisheries throughout tropical and subtropical seas.
The main source of information for some stock assessments are from commercial fisheries data, but the data may have some uncertainties. In this study we have unsampled and direct measurement of length data. We use this data to evaluate the stock status by yield and spawning stock biomass per recruit analyses. And compare the difference between this data and commercial catches data.
The growth parameters of Kaymaram(2000) were used for estimation of mortalities and per recruit analyses. The total mortalities ( Z ) were estimated as 1.98-2.64(/year) by the length-converted catch curves. The natural mortalities ( M ) were estimated as 0.75(/year) with the Cubillos’s(2003) equation. The fishing mortalities ( F ) were estimated as 1.21-1.89(/year). t50% was estimated as 1.83-2.19. Given tc as 0.68, according to the yield per recruit curves, the current fishing mortality was beyond F0.1 and Fmax , and spawning potential ratio was about 1%-3.4% suggesting that both growth and recruitment overfishing occurred in this stock. Therefore, the management policy should decrease fishing effort in order to keep the level of sustainable fisheries resource.
According to data and parameter estimation can find that Overseas Fisheries Development Council’s length data has high trend of the distribution. So estimation of some parameters, such as mortality and selectivity, there may be some errors.
| Identifer | oai:union.ndltd.org:TW/099NTU05279032 |
| Date | January 2011 |
| Creators | Yun-Jung Hsieh, 謝昀融 |
| Contributors | Chien-Chung Hsu, 許建宗 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 51 |
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