碩士 / 臺灣大學 / 海洋研究所 / 98 / Bigeye tuna (Thunnus obesus) is an economically important species, widely distri-buted in the tropical and subtropical waters of Atlantic, Indian and Pacific Oceans. High catch is concentrated in the western and central Pacific Ocean (WCPO), which was har-vested by a variety of fishing gears (including tuna longline, purse-seine and pole-and-line). The major fishing countries of the bigeye tuna is Taiwan, Japan and Ko-rea in which the adult was fished by longliners and the juvenile by other gear types (e.g. purse-seine). 57% of the bigeye tuna catch was taken by longliners, and 27% by purse seiners in 2007.
Standardized catch-per-unit-effort (CPUE) is the most commonly used as an index to reflect stock abundance. To obtain the actual abundance trend, possible factors in-fluencing the catch rate need to be removed by using standardization, because CPUE may differ across time, space, environment and fishing strategy etc. In this study, the generalized linear models (GLM) were applied to standardize the bigeye tuna catch and effort data of Taiwanese distant-water longline fishery from 1975 to 2007 and of Japa-nese distant-water longline fishery from 1975 to 2006 to convert the nominal efforts to effective efforts.
The non-equilibrium production model (ASPIC) was then applied to assess the stock status of the bigeye tuna in WCPO, from 1975 to 2007. The results showed that the maximum sustainable yield (MSY) of the stock was 60,710 MT, F/FMSY was 1.74 and B/BMSY was 1.342. Current catches are more than double the MSY, indicating the bigeye tuna stock is overfishing. It is suggested that catch or fishing effort in WCPO for the bigeye tuna have to decrease continuously, and that stock''s condition and develop-ment in the fisheries be monitored very carefully.
| Identifer | oai:union.ndltd.org:TW/098NTU05274008 |
| Date | January 2010 |
| Creators | Hui-Jhen Chen, 陳惠貞 |
| Contributors | 孫志陸 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 71 |
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