English  |  正體中文  |  简体中文  |  Items with full text/Total items : 28611/40649
Visitors : 613295      Online Users : 74
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/987654321/25074

Title: Different Spatiotemporal Distribution of Argentine Short-Finned Squid (Illex argentinus) in the Southwest Atlantic during High-Abundance Year and Its Relationship to Sea Water Temperature Changes
Authors: Chih-Shin Chen;Wen-Bin Haung;Tai-Sheng Chiu
Contributors: NTOU:Institute of Marine Affairs and Resource Managemen
Keywords: Illex argentinus;Distribution;Migration;Temperature;Patagonian Shelf
Date: 2007
Issue Date: 2011-10-20T08:21:13Z
Publisher: Zoological Studies
Abstract: abstract:The catch of Argentine squid (Illex argentinus) in the Southwest Atlantic began in the early 1980s, reached a historical high in 1999,
and dropped thereafter. By using retrospective catch information of Taiwanese jiggers to represent years of low (1996) and median (1998) catches in contrast to the historical high, we outlined an ordinary pattern of abundance for the winter cohort during the dominant fishing phase from Mar. to May, and applied step-by-step generalized linear models to look into possible causes for the high catch. The variations in catch per unit of effort (CPUE) corresponding to the 5 variable effects of year, month, latitude, position on the continental shelf, and body size were analyzed, and the findings were mapped spatiotemporally. In the 1st step, we confirmed that the high abundance of 1999 was significant at p < 0.05 as compared to ordinary years (1996 and 1998). In the subsequent intra-annual comparisons, effects of month, latitude, and body size affected the CPUE in ordinary years, while only latitude and body size were significant to the CPUE and monthly differences were irrelevant in the high-abundance year (1999). The spatiotemporal patterns in 1999 were unique; characterized by a ignificantly high catch rate which was widespread over the fishing ground, relatively small body sizes, a concentrated geographic distribution prone to southern latitudes, and little signs of a northerly (pre-spawning) migration. The cause of these characteristics could be explained by deviations in subsurface water temperatures at fishing sites. During the austral autumn of 1999, the thermal retention of waters on the Patagonian Shelf experienced a rapid decrease. Specifically, the temperature began to drop in Apr., becoming lower than in ordinary years (supported by > 90% bootstrap possibility) in middle latitudes. The lower water temperature in Apr. might have retarded the growth of the squid, consequently causing the population to remain on the nursery ground, and ultimately delaying the timing of the northerly migration of the squid for spawning. The stagnation of a high concentration of squid in the middle and southern latitudes of the Patagonia Shelf may have resulted in extensive fishing practices that further reduced the size of the potential spawning population.
Relation: 46(3), pp.362-374
URI: http://ntour.ntou.edu.tw/handle/987654321/25074
Appears in Collections:[海洋事務與資源管理研究所] 期刊論文

Files in This Item:

File Description SizeFormat

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