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研究報告

更新日期: 2015-02-09
點閱數: 1,639

氣候變遷對遠洋鮪類資源及漁場變動之影響

年度 2013
計劃名稱 氣候變遷對遠洋鮪類資源及漁場變動之影響
中文摘要 「氣候變遷對遠洋鮪類資源及漁場變動之影響」之中文摘要: 一、「氣候變遷對太平洋及大西洋鮪旗魚類漁海況之影響分析」       本研究基於歷年之研究基礎,嘗試利用已建立之評估方法,配合不同尺度的海洋遙測資料及未來氣侯情境模擬資料,分析太平洋及大西洋之長鰭鮪、黃鰭鮪、大目鮪及劍旗魚漁況的未來可能變遷,標示可能的衝擊熱區,再探討產業或管理可能遭遇的問題。研究結果顯示,在A1B情境下,2050年時各主要鮪類在不同海域漁況衰退程度各異,但衰退率大多達到50%以上。太平洋漁況衰退熱區主要分佈於0°N以北及20°S以南,北太平洋衰退熱區分佈較南太平洋廣泛,而在大西洋以低緯度及非洲西部海域漁況衰退熱區的分佈最為廣泛。由於部分魚種經驗模式之解釋能力較低,加上環境因子情境模擬資料的不確定性,應保守看待目前之評估結果,並進一步由模式優化與更新的模擬數據提昇評估之信度。 二、「氣候變遷對印度洋鮪旗魚類漁海況之影響分析」        本研究利用年我國印度洋鮪釣漁船之相關統計資料,並蒐集情境模擬(A1B、A2和B1)氣候變遷下之印度洋海洋環境資料(SST和SSH),利用泛加成模式(GAM)與GIS系統探究氣候變遷對印度洋鮪旗魚類分佈與資源變動特性之關係。 由A1B、B2和A2三種情境模擬之SST和SSH觀測不同情境下氣候變遷對印度洋海洋環境變動的影響,結果顯示於A2情境下SST與SSH上升最為顯著,其中又以印度洋赤道熱帶漁區SST上升較副熱帶高緯度地區高,而SSH在不同情境模擬上同樣顯示逐漸上升的變動情形,其中又以東西北三面環繞陸地之阿拉伯海與孟加拉灣漁區SSH上升的趨勢最為顯著。另外以長鰭鮪為例,利用GAM逐步分析法所挑選出最適合模式之解釋變量高達65.9%,其中時間因子的變動不大,然而空間因子對長鰭鮪CPUE有較高的影響,另外環境因子則顯示CPUE會隨著SST的增加和SSH的下降呈現負向的變動趨勢。再將GAM最佳模式所預測之各區域CPUE與名目CPUE進行迴歸分析,結果顯示長鰭鮪名目CPUE與預測值呈現線性正相關,且R值高達0.81。進一步利用GAM預測模式分析A2情境模擬下,如表水溫與海表面高度持續升高時,印度洋長鰭鮪之釣獲率皆會呈現持續下降的趨勢,特別為高CPUE之南印度洋副熱帶海域下降幅度為最大,其預測結果顯示該海域於2075年時CPUE約較2008年減少10~15%。另外各季預測CPUE空間分布圖顯示,第三與第四漁區之預測CPUE則呈現季節上的變動,第四漁區顯示於2075年時,除高緯度海域之CPUE會較2008年上升約0~5%以外,其他海域之CPUE皆呈現明顯下降的情形。
英文摘要 Abstract of "The impact of climate change on resources and fishing ground of distant-water tuna fisheries": 1. "Impact of climatic change on major tuna stocks in the Pacific Ocean and Atlantic Ocean" :      Based on the study of previous years, we try to evaluate the possible change trend of albacore, yellowfin, bigeye tunas and swordfish by utilizing the methodology established and multi-scale data of remote sensing as well as the future climate scenario simulation provided by IPCC. We aim to identify hotspots with climate impact and discuss future problems faced by industry and management. The result indicated that under A1B scenario hook rate of most area of the two Oceans will decrease over 50% in spite of the variation among species. In the Pacific Ocean, the hot spot of hook rate decline may occurs between 0°N and 20°S but those for North Pacific are dispersed. In the Atlantic Ocean, relatively high decreased areas are located in waters of low latitude and west of Africa. Due to empirical model for some species has low variance explained and high uncertainty of environmental simulation factors, we should be very conservative about the present evolution before we have carried out the latest evolution with improved model and more up-to-date IPCC simulation data. 2. "Effects of climate change on the tuna and billfish fishery Indian Ocean" :       The purposes of this study were to investigate whether the climatic and marine environmental variations affect catche and distribution of tunas in the Indian Ocean. We modeled the effect of SST warming in a site-selection model i.e., scenarios given in the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC, 2007). The longline fishery data were used to evaluate transient relationships of the marine environmental change with catch rates and distributions of the fishing grounds and were also used to predict potential albacore habitats. Spatial distributions of nominal CPUE showed that high CPUE values were mainly concentrated in the southern Indian Ocean. The scenario SST and SSH showed the SST and SSH were increased from 2001 to 2100, especially SSH were increased faster in the Arabian Sea and Bay of Bengal. All variables included in the GAM selection process were significant (p<0.01). The cumulative deviance explained by the selected GAM model was 65.9%. A normal quantile-quantile plot fitted to examine sample versus theoretical quantiles shows a nearly straight 1:1 line, implying that application of a Gaussian distribution was ideal. Almost half of the explained deviance was associated with longitude and latitude, and the CPUE also showed the negative and positive correlation with SST and SSH, separately.To predict spatial patterns of potential albacore habitats, statistical models were applied with the GAM model. The result showed the CPUE were decreased in the A2 scenario in the Indian Ocean. It indicated that CPUE were decreased about 10~15% in the southern Indian Ocean in the 2080 based on the 2008. However, the CPUE of albacore were increased about 0~5% in the high latitude area in the Indian Ocean.
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