English  |  正體中文  |  简体中文  |  Items with full text/Total items : 26988/38789
Visitors : 2349658      Online Users : 32
RC Version 4.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Adv. Search

Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/25531

Title: Distribution of bigeye tuna (Thunnus obesus) in relation to variability of net primary production in the Pacific Ocean
Authors: Yi-Hui CAI;I-Hsun Ni;Hsueh-Jung Lu
Contributors: NTOU:Department of Environmental Biology and Fisheries Science
Date: 2008
Issue Date: 2011-10-20T08:24:28Z
Publisher: The 4th International Symposium on FISH-GIS/Spatial Analyses in De Niro, Brazil
Abstract: abstract:The catch per unit effort (CPUE) and spatial distribution of bigeye tuna (BET) caught by Taiwanese longline varied annually, which is particularly significant in the Equatorial region during El Niño period. Basin-scale variability of sea surface temperature (SST) and chlorophyll a (chl-a) are two major ocean surface factors that often used to describe habitat range or even to locate tuna fishing ground of tunas. However, for BET in correlations with temporal average of SST, chl-a and CPUE are always poor due to complexity of ocean process and fish behaviors. In this study, we use Eppley-vertically Generalized Production Model (VGPM), a “chlorophyll-based” algorithm incorporated factors of surface chl-a, surface irradiance, SST and day length, to compute net primary production (NPP) values. Fishing efforts from September 1997 to December 2005 were separated into Deep Longliner (DLL) and Regular Longliner (RLL) by hooks per basket (HPB): if HPB≦12 named RLL whereas HPB≧13 named DLL. Then we matched the monthly maps of NPP and BET CPUE, and found that the BET CPUE of DLL in number (N/1000hooks) was significantly restrained in high NPP area where CPUE in weight (Kg/1000 hooks) were much higher than RLL’s. BET CPUE of RLL was mostly located in areas surrounding lower NPP area, with little exception in the high NPP area. The movement of the high NPP area can result in significant shift of BET CPUE in both DLL and RLL, especially during El Niño and La Niña periods. Therefore, the variability of net primary production is an explainable variable to explain variability of BET CPUE distribution in the Pacific Ocean. However, during the El Niño and La Niña periods the fluctuations of BET CPUE were more than NPP’s effects. We also analyze the subsurface water temperature data (include MLD) to discuss the physical effect of vertical structure on BET’s spatial distribution.
URI: http://ntour.ntou.edu.tw/handle/987654321/25531
Appears in Collections:[環境生物與漁業科學學系] 演講及研討會

Files in This Item:

There are no files associated with this item.

All items in NTOUR are protected by copyright, with all rights reserved.


著作權政策宣告: 本網站之內容為國立臺灣海洋大學所收錄之機構典藏,無償提供學術研究與公眾教育等公益性使用,請合理使用本網站之內容,以尊重著作權人之權益。
網站維護: 海大圖資處 圖書系統組
DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback