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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/33928

Title: 美洲大赤魷資源評估研究
Authors: 陳志炘
Contributors: 國立臺灣海洋大學:海洋事務與資源管理研究所
Keywords: 資源耗減估計法;漁業管理;美洲大赤魷;東太平洋;魷漁業
Depletion estimate methods;Fisheries management;Dosidicus gigas;East Pacific;Squid fishery
Date: 2010-02
Issue Date: 2013-07-26T06:53:56Z
Publisher: 行政院農業委員會
Abstract: 摘要:美洲大赤魷為東太平洋生態系的重要組成物種,其商業性漁捕於近年亦明顯成長,因此探究其資源量變動及空間分布改變(族群擴張)之可能原因,及其對海洋生態系與漁業之潛在影響,成為研究人員及管理者的主要興趣(Field et al., 2007; Zeidberg & Robison, 2007; Rosa & Seibel, 2008)。 魷類資源的短生命週期特性,使其族群參數易受環境狀態改變之影響(Waluda et al., 2001)。 因此,建立魷類資源量與環境參數的經驗模式,已成為探討魷類族群資源量變動的另一選擇(Pierce and Boyle, 2003)。 最近研究顯示,海洋環境狀態可能對魷類資源之資源量變動與空間分布提供相當的解釋能力(Anderson and Rodhouse, 2001; Agnew et al., 2002; Waluda & Rodhouse, 2006)。雖然環境因子已證實在魷類添加過程具重要影響,但此類因子難以控制或預測。 資源評估模式則提供資源狀態的基礎科學資訊,可支援漁業管理之規畫。目前應用於魷類資源量評估的方法為DeLury depletion method (Rosenberg et al., 1990; Basson et al., 1996)。 此模式假設分析對象為封閉族群,而族群量的耗減主要受漁業影響。 為降低洄游之影響,通常假設CPUE高峰期代表資源之完全添加(recruitment)。 由模式估算當年添加量(期初資源量)大小及漁獲能率(catchability)。 漁業管理目標為維持安全範圍的產卵族群量(Spawning stock bioass, SSB),以確保次年添加量的水準。 因此須估算每年的比例逃逸量(Proportional escapement,在漁獲死亡率下的產卵資源量,與無漁獲死亡率的產卵資源量比值)為參考點。 管理措施則有努力量控制(限制漁業執照數),及漁期長短(Beddington et al., 1990)。 雖然對短生命週期物種而言,漁期間即時(real time)的評估與管理較為有效,但往年的資源量估算仍可提供資源量變動趨勢之訊息。 本計畫擬解決問題有:1) 應用DeLury模式,估算2002-2008年大赤魷之期初資源量及逃逸比例;2) 探討漁業及環境因素對大赤魷資源量變動之可能效應,及其在漁業管理之應用;3) 持續收集大赤魷漁業之漁獲資料,更新並維護電子資料庫系統,以支援區域性漁業管理組織之需要。工作項目實施方法:1.漁業資料處理1)由中華民國對外漁業合作發展協會提供美洲大赤魷漁獲資料。 其紀錄包括:船別、日期、經緯度及漁獲量(重量)。3)利用採樣之生物資料,將漁獲量由重量(catch in weight),轉換為尾數(catch in number)。2)計算每月之單位努力漁獲量(Catch per unit effort, CPUE)為資源量指標,其中努力量為船日數(vessel-day)。2.模式套適1)由月別CPUE趨勢,決定模式套適期間。 假設大赤魷資源量於CPUE峰值時完全添加(recruit),則此後資源量耗減為漁業影響。2)應用基本DeLury模式估算每年之期初資源量及逃逸比例。3)探討年間資源量變動的可能原因,由逃逸比例探討可行的漁業管理措施。 預期效益為:1) 瞭解美洲大赤魷資源狀態與資源量變動趨勢。2) 探討影響資源量變動之可能因素。3) 提供規畫漁業管理措施之參考。
abstract:Jumbo squid is one of the important component in the ecosystem of East Pacific Tropical. The commercial fishery on this species has increased since late 1990s. The cuases of the variation in abundance and range expansion, and the potential effects on marine ecosystems and fisheries are of major interest to researches and resources managers. The characteristics of short lifespan for cephalopod populations make them vulnerable to the change of environmental conditions. Thus, to establish the empirical models between variation of squid abundance and environmental factors have been used as an alternative option in evaluate the variations of squid abundance. Recent studies have demonstrated that oceanographic conditions could explain to a degree the variation of squid abundance and spatial distribution. However, environmental factors cannot be controlled or predicted. Stock assessment provides the basic scientific information on the status of the stocks, and can be applied in the management procedure.The appropriate methods used for squid stock assessment is depletion estimate method. At present, depletion methods are successfully spplied in the management of squid fisheries around the Falkland Islands. In basic depletion methods, the stocks are assumed to decrease because of fishing, i.e. the natural mortality rate is negligible. The period of peak CPUE is assumed to reflect the complete recruitment. The model can estimate the initial population size and catchability coefficient. The management objective is to allow enough escapement of spawning stock biomass which can sustain recruitment in next year. Proportional escapement was suggested as a reference point. The main management measures is the control of fishing effort, by limiting the number of licences and the duration of fishing season. The questions to be addressed in this projects are: (1) to apply depletion method to estimate the stock size of jumbo squid in 2002-2008; (2) to address the implications of stock status on fisheries management; (3) to maintain the database of catch and effort data of jumbo squid fishery. Workin items:1.Fisheries data(1) Re-structured catch-effort data of jumbo squid fishery.(2) Convert the data from catch in weight to catch in number. (3) Calculate monthly CPUE as abundance index. 2.Depletion method(1) Select the appropriate period for model fitting.(2) Apply depletion method to estimate initial population size and catchability coefficient.(3) Discuss the annual trend of abundance variation and the implications for fisheries management.The expected results are,(1) To understand the status of stock and interannual variation patterns of jumbo squid.(2) To analyse the possible causes for the variation of squid abundance.(3) To support the basic scientific information for fisheries management procedure.
Relation: 99農科-10.1.1-漁-F5(2)
URI: http://ntour.ntou.edu.tw/handle/987654321/33928
Appears in Collections:[海洋事務與資源管理研究所] 研究計畫

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