博士 / 國立臺灣大學 / 海洋研究所 / 89 / Abstract
When applying the mathematical model in estimating the fishery resource, the deviation is mainly resulted from the system and observation errors. For example, to estimate the stock status of albacore in the Indian Ocean by surplus production model, the target species have shifted for the fishery structure change in Taiwan longline fishery. The data of effort target on different species was not separated in the logbooks that resulted in the observation error. Therefore, the error should be treated to make the estimate closer to the real fishery situation when applying the model.
The fuzzy synthesis was applied to segregate the effort data that belongs to two kinds of Taiwan longline operations, i.e. the regular longline that target on the albacore and the deep longline that target on the bigeye tuna and yellowfin tuna. Four factors, i.e. the temporal and spatial factor, the hook used, the size of the vessel and the sea surface temperature, are used. A criteria by fuzzy transformation from weighting vector of the above four factors and from fuzzy relationship between the four factors and the two kinds of operation was obtained to separate the effort data. The general linear model was used to standardized the separated catch effort data of regular longline operation and then to obtain the adjusted catch per unit effort series as abundance index. A weighting average of the adjusted catch per unit effort of Taiwan tuna longline and Taiwan gillnet fisheries was used as the abundance index of the albacore in the Indian Ocean. The abundance index of the Indian albacore showed that the series keep stationary fluctuation from 1979-1984 except the depression in the period of 1985-1992. then keep increase for the last two years.
The maximum sustainable yield (MSY) estimated by Schaefer surplus production model is about 27,717 M.T. MSY estimated by fuzzy surplus production model is fuzzy number. The center of the fuzzy MSY ranged from 25,728-30,651 M.T. with the increasing vagueness. MSY of this study are higher than those of the previous studies and closer to those of the recent studies. The stock status of the albacore in the Indian Ocean was under full exploitation. As to the fuzzy surplus production model that was built as substitution for Schaefer surplus production model needs more advanced research in the future searching for the optimum MSY as the management criteria in the fishery.
| Identifer | oai:union.ndltd.org:TW/089NTU00279044 |
| Date | January 2001 |
| Creators | ShuHwei Wang, 汪淑慧 |
| Contributors | Hsu Chien-Chung, Liu Hsi-Chiang, 許建宗, 劉錫江 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 92 |
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