碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 103 / Bigeye tuna (Thunnus obesus) is one of the important commercial species of the Taiwanese longline fishery in the Indian Ocean. In this study, we collected the Taiwanese LL data, environment variables and climate index during the period of 1998-2011. The Generalized Additive Models (GAM) was used to explore the correlation between deep longline (DLL) catch rate of bigeye tuna (CPUE), oceanic environmental factors and climate index to evaluate the impacts of climate variability on the spatial distribution of bigeye tunas.
The model selection processes of GAMs showed the cumulative deviances explained were 46.9%. The results showed the catch rates were significantly correlated with the temporal (year and month), spatial (longitude and latitude), environmental variables of sea surface temperature (SST), net primary production (NPP) and mixed layer depth (MLD) and climate index (dipole mode index (DMI) and Nino3.4 index). We observed a positive association between catch rates and SST between 27-29°C, around 250-400 mgC/m^2 d^1 of NPP and MLD within 40-60 m. The result also shows the positive correlation with climatic indices (DMI and Nino3.4) and standardized CPUE. The higher predict CPUE co-occur with higher SST, lower NPP and shallower MLD.
The analysis of fishing catch gravity illustrated the seasonal movement of potential fishing ground. Whem the DMI is positive value, the fishing catch gravity would shift westward and shift to eastward in the negative value. In the El Niño years, the fishing catch gravity would shift westward and shift to eastward in the La Niña years. These findings from satellite remote sensing provide preliminary insights into some of the climate variability driving the environmental changes on the catch rate and spatial distribution of bigeye tuna in Indian Ocean.
| Identifer | oai:union.ndltd.org:TW/103NTOU5451024 |
| Date | January 2015 |
| Creators | Chen, Yu-Hong, 陳昱宏 |
| Contributors | Lee, Ming-An, Lan, Kuo-Wei, 李明安, 藍國瑋 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 82 |
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