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Establish GIS-based empirical model of habitat suitability for yellowfin tuna in the Western and Central Pacific Ocean
|Authors: ||Kuo-Wei Yen|
|Contributors: ||NTOU:Department of Environmental Biology and Fisheries Science|
Geographic Information System;habitat suitability index;purse seine;remote sensing
|Issue Date: ||2011-06-30T08:27:37Z
|Abstract: ||以經驗模式之分析方法探討物種的棲地適合度指數(HSI)，已經廣泛應用於探討多種動物棲地之優劣，但鮮少應用於大洋上高度洄游的物種鮪魚上。本研究嘗試以地理資訊系統(GIS)整合2003至2007年我國鰹鮪圍網漁獲資料與衛星遙測之海表環境參數，包括海水表面溫度(SST)、海水表面葉綠素濃度(SSC)、海水表面高度(SSH)及海水表面鹽度(SSS)，分析中西部太平洋黃鰭鮪的棲地適合度。利用研究期間所有黃鰭鮪素群漁獲位置的各個環境參數值出現之頻度，轉換個別之適合度指數(SI)，再計算3種不同HSI之經驗模式，最後利用泛線性模式篩選出最佳的經驗模式，並分析研究區域之HSI變動，主要結果如下： (一) 黃鰭鮪偏好水域的SST值介於27.2～32.5 ℃、SSC值介於0.02-0.18 mg/m3、SSH值介於1.51～2.23 m、SSS值介於34.22-35.25 psu。 (二) 研究區域之黃鰭鮪HSI最佳經驗模式算法為，將SST、SSC、SSH及SSS轉換成SI後取四者之算術平均數，其預測黃鰭鮪的準確率高達71.97%。 (三) 研究區域之HSI每年3～4月開始上昇，範圍擴大，高HSI水域向東延伸，11月至隔年2月快速下降，HSI變動與黃鰭鮪之漁獲量增減及CPUE分佈移動具有一致性。 本研究以四種常用的遙測表水文資料推估HSI，證實可作為黃鰭鮪大範圍棲地適合度變動的指標，未來應可直接應用於衡量氣候變遷衝擊下適合度的改變。但若欲作為漁場搜尋層次的指標，則因遙測資料之時間解析度限制，以及深層水文之影響未列入考量，仍需有諸多待努力之處。|
Empirical Habitat Suitability index (HSI) has been widely used to examine the quality of terrestrial animal, but rarely used in highly migratory fish like tuna. In this study, we used GIS technique to establish empirical models of HSI for yellowfin tuna (YFT) in the Western and Central Pacific Ocean (WCPO). Daily catch data from Taiwanese purse seiner fishery during 2003-2007 were aggregated monthly into 1 by 1 degree and then conduct data match process to obtain monthly average values for the multi-environmental factors, including sea surface temperature (SST), chlorophyll-a (SSC), height (SSH) and salinity (SSS). According to the frequency distribution of each factor on which YFT were caught, we transformed the values of the 4 factors into suitability index (SI) ranged from low to high (0-100%). These SI values were then combined into different empirical HSI models and the optimum one were selected by General Linear model. With the HSI, we have the major results of the analysis are as follows: 1. The optimum ranges of SST, SSC, SSH and SSS for YFT are 27.2～32.5 ℃, 0.02-0.18 mg/m3, 1.51～2.23 m and 34.22-35.25psu. 2. The optimum empirical HSI for TFT’s in the study area is converting the for SI (SST, SSH, SSC and SSS) by arithmetic mean model, by which the correct prediction rate is 71.97%. 3. The HSI began to increase and expand eastwards in March to April and rapid declined in November to next February in the study area. There was an agreement between the average HSI and total YFT catch. Also the high HSI area synchronized with the displacement of CPUE. In this study, we used 4 kinds of surface variables derived from satellite to develop HSI for YFT in the WCPO. The HSI has been proved to a valid index for YFT habitat suitability in large-scale ocean and should be useful to measure the overall habitat able trend for YFT under future climate change in the region. However, the HSI is still unable to be used for fishing ground search due to the limitation of remote sensing data in temporal scale and the lack of subsurface information. There are more effort need to be further inserted for a more applicable HSI in operational level.
|Appears in Collections:||[環境生物與漁業科學學系] 博碩士論文|
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