模糊多目標函數應用於改善養殖漁業型態之研究──以彰化縣大城鄉為例

A Study on Application of Fuzzy Multi-Objective Function for Improving the Aquaculture Condition in Ta-Chen, Chang-Hwa

為有效減緩沿海地區地層下陷持續惡化，如何減少地下水超抽已成為重要的課題。其中，對於如何降低養殖業者大量抽用地下水之情況，除了可開發地表水源以提供養殖用水外，另可從調整養殖漁業結構之方向著手，使其達到降低養殖用水量並提昇養殖利潤。鑑於彰化縣大城鄉之地層下陷情況嚴重且境內以抽用地下水養殖高耗水量之蜆為主，本研究將考量引進其它養殖用水方式與引進其它較高經濟價值且低淡水耗量之淡水魚種或低鹽度鹹水魚種，以降低該區域對地下水之依賴。本研究擬利用模糊多目標函數為分析工具，以綜合考量降低海水用量、淡水用量與提昇養殖利潤等三個單目標，同時利用全域最佳化參數搜尋方法求解合適的養殖用水情境。本研究以合理減少養殖用水同時兼顧養殖利潤之方式進行養殖用水情境模擬，未來將可提供漁業主管機關進行養殖漁業結構調整與輔導之參考。 In order to prevent land-subsidence from getting worse, decreasing ground water use is necessary. Therefore, in addition to providing surface water for aquaculture freshwater demand, arranging the aquaculture structure is the other way for reducing the freshwater demand and increasing the total fisheries margin. Due to the serious land-subsidence in Ta-Chen, Chang-Hwa, which may be caused by overusing groundwater for mainly raising freshwater clams in this area, alternative techniques for water usage and changing the kinds of fish with a higher fisheries margin and less freshwater demand were tried to release the groundwater dependence. The fuzzy multi-objective function comprising three single objectives, viz. reducing saltwater demand, reducing freshwater demand, and increasing the total fisheries margin, was utilized with a global optimization algorithm to find suitable aquaculture scenarios in this area. Results of the proposed method can be provided to the fisheries authorities as references for arranging the aquaculture structure.